In a crash rear-seat passengers in a vehicle can fly ahead with first-rate force injuring or killing passengers in the front seat. Option A.
There is a common misconception that people are safer in the back seat, but the reality is that rear-seat passengers who are not buckled up are more likely to die in a crash. Upon impact, they're often thrown forward into the back of front seats with significant force. Sit upright and you will have the least chance of getting an auto injury.
It will keep you secure and will lower your risk for serious injury. Headrests also protect you in the event of an accident. consistent with a recent study by the Insurance Institute for Highway Safety IIHS the back seat is no longer the safest place. In fact, sitting in the front seat increases your chances of surviving a car accident.
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what is the force of an object that has a mass of 20 kg and is accelerating at a rate of 15 m/s/s
22. Determine If you walked 20 m, took a book from a library table, turned around and walked back to your seat, what are the dis tance traveled and displacement? please answer in full sentences
Answers:
Distance = 40 meters
Displacement = 0 meters
============================================
Reason:
The distance traveled is simply the sum of the two distances 20 and 20 to get 20+20 = 40. It's what anyone would expect when they ask "how far did the person travel in total?"
The displacement is the change in position from start to end. In this case, the student ends up back where they started, meaning no change has happened. If the teacher closed their eyes and opened them after the student gets back, then for all the teacher knows, the student hasn't moved at all.
Put another way, displacement tells us how far away the student has ended up compared to the start position. But since they went back to the start, no change has occurred.
to negotiate a flat (unbanked) curve at a faster speed, a driver puts a couple of sand bags in his van aiming to increase the force of friction between the tires and the road. will the sand bags help?
Given the fact that the friction between the van and the road would increase, then the sand bags would help.
What is friction?The term friction has to do with the force that opposes the movement of an object on another. This in a sense implies that the frictional force is a resistive force. It can help to slow an object down and this is why the braking system of a car operates on the principle of friction.
Now, we are told that to negotiate a flat (unbanked) curve at a faster speed, a driver puts a couple of sand bags in his van aiming to increase the force of friction between the tires and the road.
The task is to determine if the sand bags would be of help. We have to note that the sand bags would help to increase the friction between the car and the road so it would definitely be of help.
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how do astronomers measure that sunspots come in north pole / south pole magnetic pairs? how do they view the sun's magnetic field? from helioseismology and doppler shifts spectral lines can be split into multiple lines, further apart the stronger the magnetic field is from neutrino telescopes revealing where the proton-proton chain is broken from the motion of iron filings naturally streaming out of the radiation zone
The Zeeman effect, a feature of atoms, is used to quantify the solar magnetic field. To do this, scientists look at the spectral lines that originate from sunspots and calculate by how much these lines are split.
The Zeeman effect is the result of a spectral line splitting into many components when a static magnetic field is present. It bears the name Pieter Zeeman after the Dutch physicist who made the discovery in 1896 and won the Nobel Prize for it. The magnetic dipole interaction between the nuclear spin moment and the internal magnetic field at the nucleus is what causes magnetic splitting (also known as the nuclear Zeeman effect). Three different varieties of the Zeeman Effect can be seen: the standard Zeeman effect, the anomalous Zeeman effect, and the diamagnetic Zeeman effect. The Zeeman effect is the splitting of atomic energy levels caused by an external magnetic field. This effect is also known as the Bohr's Magneton and is further characterised by orbital and spin angular momentum.
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6. What is the acceleration of a 15 kg object being pushed with 200 N of force?
The acceleration of the object will be 13.33 m/s^2.
According to Newton's second law of motion,
The magnitude of Force is equal to the product of the mass of the body and the acceleration it is given ( or achieves ).
The units of force, mass and acceleration are Newton, kg and m/s^2 respectively.
In numerical terms,
Force = mass × acceleration
i.e. F = m × a
Given,
mass of the body = 15 kg
Force applied to the body = 200 N.
Putting these values in the equation,
200 = 15 × a
=> a = 200/15
=> a = 13.33 m/s^2.
Therefore, the acceleration of the given body will be 13.33 m/s^2.
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A box measures 3 centimeters on each side and has a mass of 47 grams , what is the density
Answer:
[tex]3 \times 47 = [/tex]
141
An atmospheric layer of a specific gas provides shielding from harmful ultraviolet light from the sun, allowing life to thrive on earth. What gas makes up this layer?.
The gas that makes up this layer is O3 (Ozone).
The ozone layer protects the earth from most of the sun's UVB rays. Greenhouse gases are a set of gases that accumulate in the lower layer of the atmosphere the troposphere and absorb infrared radiation to increase the average temperature of the Earth's surface. At the top of the stratosphere, 30 miles up, ozone absorbs most of the sun's harmful UV rays.
At the top of the troposphere 12 miles, up ozone acts as a greenhouse gas and traps heat. The troposphere is the lowest layer of the Earth's atmosphere. Most of the atmospheric mass is in the troposphere. Most types of clouds are in the troposphere, and almost all weather phenomena occur in this layer. Greenhouse gases are so named because they absorb infrared radiation from the sun in the form of heat which circulates in the atmosphere and is eventually lost to space.
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imagine you are outside enjoying the warm sunshine with friends. as you briefly glance up at the sun, the part of the sun that you can see directly is called its:
Find the x-component of this
vector:
12.1 m
48.4°
The resultant distance of the vector is 12.1 m and the angle between two vectors are 48.4°. So the x-component of this vector is, Aₓ = 8.0335 m
What is vector?Vector is a product that means a parameter has two types of property one is value second is direction. If a parameter has both then it called a vector quantity. Example: Velocity.
How can we calculate x-component of this vector?To calculate the vector we know first this is a proper vector quantity or not. According to the question, this is a vector quantity. So it has two component, one along x axis another is y axis as shown in the picture.
We have to calculate the x-component, so we are using the formula is,
Aₓ = Acosθ
Here we are given,
A = The resultant distance of the vector = 12.1 m
θ= The angle between two vectors = 48.4°.
Now We have to calculate the x-component = Aₓ
Now we put the known values in the above equation, we get
Aₓ = Acosθ
Or, Aₓ = 12.1*cos(48.4°)
Or, Aₓ = 8.0335 m
According to the calculation we get, the x-component of this vector is, Aₓ = 8.0335 m
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Answer:
Explanation:
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A force of 2.0 × 102 newtons is applied to a lever to lift a crate. If the mechanical advantage of the lever is 3.43, what is the weight of the crate?
A force of 2.0 × 10² newtons is applied to a lever to lift a crate. If the mechanical advantage of the lever is 3.43, then the weight of the crane would be 686 Newtons.
What is the mechanical advantage?Mechanical advantage is defined as a measure of the ratio of output force to input force in a system, It is used to analyze the forces in simple machines like levers and pulleys.
Mechanical advantage = output force(load) /input force (effort)
As given in the problem a force of 2.0 × 10² newtons is applied to a lever to lift a crate. If the mechanical advantage of the lever is 3.43,
The weight of the crane = 200 × 3.43
= 686 Newtons
Thus, the weight of the crane would be 686 Newtons.
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If a car travels 1,000 m in 60 seconds how fast is it going?
Answer:
see below
Explanation:
1000 m / 60 s = 16 2/3 m/s
Need help putting all of these in the correct spots.
Physical property- color, density, melting point, boiling point, hardness Chemical property- neutralizes an acid, reacts with base to form water, reacts with water to form gas, neutralizes a base, flammability.
What is the physical property?A quality of matter that is unrelated to a change inside its chemical makeup is called a physical property. Density, colour, hardness, melting & boiling points, and conductivity are a few common instances of physical qualities.
How are physical properties observed?Without altering the makeup of the substance, physical qualities can be seen or quantified. In order to observe and describe matter, physical attributes are used. The following are only a few examples of physical characteristics: appearance, texture, colour, smell, melting and boiling points, density, solubility, polarity, and many more.
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select the best answer. the logarithmic decrement is: a. the ratio of the damping in the system to the critical damping b. the ratio of the successive amplitudes in a time series c. the ratio of the damping in one system compared to another system d. the total damping present in the system
Logarithmic decrement is the ratio of successive amplitudes in a time series.
The logarithmic decrement δ is equal to the natural logarithm of the ratio of two successive maximum deflections x of oscillating quantity in the same direction:
δ = log( [tex]x_{1} /x_{2}[/tex])
Logarithmic decrement is used to find the damping ratio of an underdamped system in the time domain. It is defined as the natural logarithm of the ratio of any two successive amplitude on the same side of the mean line.
Therefore we get that logarithmic decrement is the ratio of successive amplitudes in a time series.
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If two covalently bonded atoms move closer than a distance of the bond length, the potential energy of the atoms.
If two covalently bonded atoms move closer than a distance of the bond length, the potential energy of the atoms increases
Which bond possesses the highest possible energy?Stronger bonds have lower potential energy than weaker ones. The weaker connection has a higher potential energy. Ionic bonds are stronger than covalent ones, hence covalent bonds have higher potential energy.
The tremendous repulsive interactions between the positively charged nuclei of the bound atoms cause the energy of the system to dramatically rise if the atoms move closer to one another than the ideal bond distance.
If there is an attractive force between the two, the potential energy will rise with more separation, but if there is a repulsive force, the potential energy will fall with greater separation.
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two automobiles, each of mass 800 kg , are moving at the same speed, 18 m/s , when they collide and stick together. at what speed does the wreckage move if one car was driving north and one east?
14.14 m/s speed does the wreckage move if one car was driving north and one east
Based on the moment of momentum conservation in the x-direction,
1000 20 = (1000 + 1000) yields v _y v y = 10 m/s.
result = 14.14 m/s
What makes momentum so crucial?An object's mass, velocity, and direction are all related by momentum. Force arises from any change in momentum. In order to ascertain the force exerted on the item, a change in momentum is utilised.
Force and momentum are distinct even though they appear to be the same physical quantity. Whether a body is being pulled or pushed, force is often defined as an outside action. The measure of how much motion there is inside a moving body is called momentum, on the other hand.
Unlike force, which refers to a push or pull action, momentum refers to the amount of motion in a moving body. Force modifies a body's momentum. While momentum varies while acceleration is constant, force does not.
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A cat wakes up in its bed and visits its food dish to the left of its bed. Positions to the right of its bed are assigned a negative value and positions to the left of its bed are assigned a positive value. Where did the cat begin and end its journey?
Time (m) 1, 2, 3, 4, 5
Position (m) 0, 2, 4, -5, -10
O The cat began its journey at its food dish and ended its journey 10 meters to the right of its bed.
O The cat began its journey in bed and ended its journey 5 meters to the left of its bed.
O The cat began its journey at its food dish and ended its journey 10 meters to the left of its bed.
O The cat began its journey in bed and ended its journey 10 meters to the right of its bed.****
The cat began its journey in bed and ended its journey 10 meters to the right of its bed.
Journey is an act of travelling from one place to another.
The cat wakes up in its bed and visits its food dish to the left of its bed.
This show that the cat's journey starts from positive value and according to the position chart it travels 2 m after waking up in the bed.Next 2 m it travels again in positive direction and reaches to value 4Then it goes towards the right side of the bed and travels to -5.It's journey ends at the right side of the bed when it reaches to value as -10.Time (m) 1, 2, 3, 4, 5
Position (m) 0, 2, 4, -5, -10
The above time table shows that the journey of the cat starts from the moment it wakes up in the bed as the timer starts the moment the cat wakes up and ends at 10 in negative direction i.e. to the right side of the bed.
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The specific heat capacity, abbreviated with the letter , is the quantity of required to change the temperature of gram of an object by 1.
The specific heat capacity, abbreviated with C the letter , is the quantity of energy required to change the temperature of One gram of an object by 1
What is Specific Heat Capacity ?The specific heat capacity is defined as the quantity of heat (J) absorbed per unit mass (kg) of the material when its temperature increases 1 K (or 1 °C), and its units are J/(kg K) or J/(kg °C).
The amount of heat per unit mass needed to raise the temperature by one degree Celsius is known as the heat capacity or specific heat. The ability to distinguish between two polymeric composites using specific heat is useful in calculating processing temperatures and the quantity of heat required for processing.Learn more about Specific Heat Capacity here:
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a child moves on x axis at a starting point 10cm it moves till it reaches point 70cm then it goes back to 5.
What's the displacement?
What's the distance?
The displacement on x-axis is 75 cm and the distance that moved by the child is 80 cm
The term displacement refers to a shift in an object's position. It is a vector quantity with a magnitude and direction. And distance is the sum of an object's movements, regardless of direction. Distance can be defined as the amount of space an object has covered, regardless of its starting or ending position.We are given that,
Starting point of child = d₁ = 10cm
Reaching point of the child = d₂ = 70cm
Move back = 5cm
Therefore, total distance covered by a child can be given as,
Δd = 10cm + 70 cm = 80 cm
Thus, the total distance is 80cm and a child moves back 5cm then the displacement would be given as,
Displacement = total distance cover - distance move back
Displacement = 80cm - 5 cm = 75 cm
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an elevator of mass m is initially at rest on the first floor of a building. it moves upward, and passes the second and third floors with a constant velocity, and finally stops at the fourth floor. the distance between adjacent floors is h. what is the net work done on the elevator during the entire trip, from the first floor to the fourth floor?
From the first floor to the fourth floor, the elevator's net work during the entire trip is -3mgh.
Given,
On the first floor of a building, an elevator with mass m is initially at rest. It ascends at a constant speed, passing second and third floors before coming to a stop at the fourth floor.
the separation between the floors is h
The distance from the first floor to the fourth floor Equals 3 hours of work = -mg(3 hours)
= -3mgh
Work Done = -3mgh
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the spacecraft voyager was launched and continues traveling in space, even though it doesn't have an engine that pushes it forward. the fact that voyager travels in space is an example of
The fact that voyager travels in space is an example of Newton's First Law of Motion.
What are Newton's Laws of Motion?
Newton's laws of motion are three basic laws of classical mechanics that describe the relationship between the motion of an object and the forces acting on it. These laws can be paraphrased as follows:
A body remains at rest, or in motion at a constant speed in a straight line, unless acted upon by a force.When a body is acted upon by a force, the time rate of change of its momentum equals the force.If two bodies exert forces on each other, these forces have the same magnitude but opposite directions.When the voyager was launched, it was already moving forward in motion. So, because of the Newton's First law of motion the voyager remained in motion as there is no air friction present in the space to stop its motion.
Thus, this situation is an example of Newton's First law of motion.
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A substance added to gasoline is found in the wells of people who live miles from a gas station. Is this an example of a point source of pollution or a nonpoint source of pollution? Explain.
I need to get it done right now
Answer:
a pipe, ditch, ship or factory smokestack.”
Explanation:
The U.S. Environmental Protection Agency (EPA) defines point source pollution as “any single identifiable source of pollution from which pollutants are discharged, such as a pipe, ditch, ship or factory smokestack.” Factories and sewage treatment plants are two common types of point sources.
if you throw a 0.4 KG ball at a speed of 20 m/s what is the kinetic energy between the balls motion
A moving item possesses kinetic energy. If we want to accelerate an object, we must exert a force. Applying force requires effort on our part. Once the process is complete and energy has been transferred to the item, it will begin to move at a new constant speed.
Kinetic energy is the energy that an object has as a result of motion. It is defined as the work required to accelerate a mass-determined body from rest to the indicated velocity. Unless its speed changes, the body retains the kinetic energy it gained during acceleration.
Using the formula - K.E. = 1/2 × m × v²
K.E. = 1/2 × 0.4 × 20²
K.E. = 80 kg m/s²
The energy of motion is called kinetic energy, and it can be observed in the movement of an object, particle, or group of particles. Any moving object, such as a person walking, a baseball being thrown, food falling off a table, or a charged particle in an electric field, utilizes kinetic energy.
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the circuit breaker that protects a power window circuit opens whenever the window is lowered. technician a says the internal resistance of the motor is too high. technician b says the window regulator may be sticking causing high mechanical resistance. who is correct?
Both technicians A and B are correct. Hence, option C.
An ammeter is used to measure the electrical current in the circuit. An ammeter should be placed into series with the circuit being tested.
The ammeter can be connected either on the power side or on the ground side of the motor but the only condition is it should be connected in the series.
Internal resistance refers back to the opposition to the float of cutting-edge supplied by using the cells and batteries themselves ensuing inside the era of heat. internal resistance is measured in Ohms. the connection among inner resistance (r) and emf (e) of cell s given through. e = I (r + R)
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Disclaimer:- your question is incomplete, please see below for the complete question.
The circuit breaker that protects a power window circuit opens whenever the window is lowered. technician a says the internal resistance of the motor is too high. technician b says the window regulator may be sticking causing high mechanical resistance. who is correct?
A. A only
B. B only
C. Both A and B
D. Neither A nor B
a projectile is launched horizontally with a speed of 80.0 m/s. if the projectile is launched from a hihg of 1.5 meter above the floor, how long does it take the projectile to hit ht efloor
The time taken by the projectile to hit the floor is 0.55 s.
What is projectile motion?The projectile motion refers to the motion of an object or particle that is launched into a gravitational field, such as from the surface of the Earth, and travels along a curved path while only being influenced by gravity. A body is considered to be in projectile motion if it moves both vertically and horizontally (trajectory) from the point of flight to the point of landing.
This indicates that the projectile is initially thrown at a height of 1.5 meters and a speed of 80.0 meters per second.
Since the bullet is launched horizontally, the initial vertical velocity component is zero. Just figure out how long it takes something to fall 1.5 meters from a seated position. The 80 m/s is only important if you want to know where it will land on the ground. It has no bearing on the situation. We might be led to the fundamental Newtonian equation:
hf = v₀t + (a/2)t² + h₀
Here, h stands for height, v for speed, and a for acceleration. It might be difficult to resolve this for t in some circumstances, however since
v₀ = 0, this one is easy.
0 = (-9.8/2)t² + 1.5
-1.5 = -4.9t²
-1.5/-4.9 = t²
0.55 s = t
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a tourist being chased by an angry moose is running in a straight line toward her car at a speed of 4.6 m/s. the car is a distance d meters away. the moose is 46.5 m behind the tourist and running at a speed of 10.8 m/s. the tourist reaches her car safely. what is the maximum possible value for d in meters?
A tourist was chased by a moose and run toward her car at a speed of 4.6 m/s. As the tourist reaches her car safely, the maximum possible value of the distance between her and the car was 34.5 m
Formula:
s = v . t
Where:
s = distance
v = velocity
t = time
The tourist reached her car safely means at minimum she had the same time with the moose to reach the car.
Tourist circumstance:
distance = d
v = 4.6 m/s
time to reach the car:
t_tourist = d / 4.6
Moose circumstance:
distance = d + 46.5
v = 10.8
time to reach the car:
t_mouse = (d + 46.5) / 10.8
t_tourist = t_mouse
d / 4.6 = (d + 46.5) / 10.8
(10.8 - 4.6) d = 46.5 × 4.6
6.2 d = 213.9
d = 34.5 m
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to measure the speed of an airplane, a narrow strip heater is attached to the wing of an airplane 0.01 m from the leading edge. a heat flux of 300 w/m2 is electrically dissipated and the temperature difference between the heater and the surrounding air is measured to be 1 oc. assume that the temperature of the wing is uniform. what is the speed of the aircraft?
The speed of the aircraft with a narrow strip heater attached = 370.97 m/s
The distance of the strip heater attached to the wing from the leading
edge, x = 0.01 m
Heat flux, q = 300 W/m²
The temperature difference between the heater and surrounding air,
ΔT = 1°C
The properties of the air are
The density of air, ρ = 1 kg/m³
Specific heat at constant pressure, CP = 1 kJ /kg K
Thermal conductivity, k = 0.02 W/mk
Viscosity, ν = 1.5 x 10⁻⁵ m²/s
Dynamic viscosity,
μ = ρ.ν
= 1 x 1.5 x 10⁻⁵
= 1.5 x 10⁻⁵ N s / m²
Prandtl number,
[tex]\displaystyle P_r =\frac{\mu. CP}{k}[/tex]
= 1.5 x 10⁻⁵ x 1 x 10³ / 0.02
= 0.75
Heat flux,
q = hₓ ΔT
300 = hₓ x 1
hₓ = 300 W / m² C
So, the local Nusselt number is
[tex]\displaystyle Nu_x = 0.332 Re_x^{1/2} P_r^{1/3}[/tex]
[tex]\displaystyle \frac{h_x.x}{K} = 0.332 \frac{v.x}{\nu}^{1/2}P_r^{1/3}[/tex]
where v is the velocity of the aircraft
[tex]\displaystyle\frac{300 * 0.01}{0.02} = 0.332 \left( \frac{v*0.01}{1.5 * 10^{-5}}\right)^{1/2} (0.75)^{1/3][/tex]
By further simplifying, we get
150 = 0.332 x 0.9085 x 25.82 x [tex]v^{1/2}[/tex]
v = 370.97 m/s
Therefore, the speed of the aircraft is 370.97 m/s
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If net force acting on object is 0, then the force is considered to be..
a. balanced
b. equal in direction
c. unbalanced
d. distance/time
If net force acting on object is 0, then the force is considered to be balanced (option A).
What is net force?A net force refers to the sum of all the forces acting on an object.
The net force can accelerate a mass. Some other force acts on a body either at rest or motion. The net force is a term used in a system when there is a significant number of forces.
Fnet = F₁ + F₂ + F₃.............+ Fn
When the net force of an object is zero (0), this means that the sum of forces acting on the object is balanced. A balanced forces are forces that are opposite in direction and equal in size.
Therefore, a net force of 0 is a balanced force.
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a ball on the end of a string is whirled around in a horizontal circle of radius 0.300 m. the plane of the circle is 1.40 m above the ground. the string breaks and the ball lands 1.50 m (horizontally) away from the point on the ground directly beneath the ball's location when the string breaks. find the radial acceleration of the ball during its circular motion.
Radial acceleration of the ball during its circular motion is 41.8 m / s².
a = v ²/ r represents the circular motion acceleration.
In addition, they provide the X and Y positions at which the body will fall if the rope breaks.
x = v₀x t,
y = v₀x t-1/2gt²
because the circle is horizontal, the value of v0x is zero (v0x = 0).
X = v₀x t
t = x / v₀x
y = - 1/2 g t²
In order to determine the initial velocity on the X axis, let's replace it with y = − 12 g (x / vox) ²
v₀ₓ = √ [ (9.8) 1.6² / (21)]
v₀ₓ = 3.54 m / s
Its circle is in a horizontal position, so in addition to being the horizontal velocity, this is also the velocity of the body at the point of rupture.
The radial acceleration is now calculated using the formula
a = v² / r
a = 3.54² / 0.300
a = 41.8 m / s²
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The element lanthanum has an isotope with an atomic mass of 138. 9 amu and an abundance of 99. 91%. A second isotope has an atomic mass of 137. 9 amu and an abundance of 0. 9%. What is the average atomic mass of lanthanum?.
The average atomic mass of lanthanum that has an isotope with an atomic mass of 138.9 amu and an abundance of 99.9 1% and a second isotope with an atomic mass of 137.9 amu and an abundance of 0.09 % is
Average atomic m = Sum of product of atomic m and % abundance / 100
For isotope 1,
Atomic mass = 138.9 amu
% abundance = 99.91 %
For isotope 2,
Atomic mass = 137.9 amu
% abundance = 0.09 %
Average atomic mass = ( 138.9 * 99.91 ) + ( 137.9 * 0.09 ) / 100
Average atomic mass = 13877.5 + 12.41 / 100
Average atomic mass = 138.9 amu
The average atomic mass or average atomic weight of an element is the weighted average mass or weight of atoms in a naturally occurring sample ( i.e., isotopes ) of the element.
Therefore, the average atomic mass of lanthanum is 138.9 amu
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A woman of mass 57.6 kg is standing in an elevator.If the elevator floor pushes up on her feet with a force of 395 N, what is the acceleration of the elevator? Assume the +y-direction to be up. Enter a negative answer if the acceleration is downward and a positive answer if the acceleration is upward.If the elevator maintains constant acceleration and is moving at 1.50 m/s as it passes the fourth floor on its way down, what is its speed 4.00 s later?
There are two forces acting on the woman: the normal force of the floor of the elevator and the weight of the woman.
First, find the weight of the woman by multiplying its mass times the acceleration of gravity:
[tex]\begin{gathered} W=mg \\ =(57.6\operatorname{kg})(9.8\frac{m}{s^2})=564.48N \end{gathered}[/tex]According to Newton's Second Law of Motion, the net force acting on an object relates to the acceleration of the object according to:
[tex]\Sigma F=ma[/tex]Since the normal force of the floor is exerted upwards and the weight is exerted downwards, then:
[tex]\begin{gathered} \Sigma F=N-W \\ \Rightarrow N-W=ma \end{gathered}[/tex]Isolate the acceleration from the equation:
[tex]\Rightarrow a=\frac{N-W}{m}[/tex]Replace the values of the normal force (395N), the weight and the mass of the woman to find the acceleration of the elevator:
[tex]\begin{gathered} \Rightarrow a=\frac{395N-564.48N}{57.6\operatorname{kg}}=-2.94236\ldots\frac{m}{s^2} \\ \therefore a\approx-2.9\frac{m}{s^2} \end{gathered}[/tex]Then, the acceleration of the elevator is 2.9 m/s^2 downwards.
Use the definition of acceleration to find the final speed of the elevator 4 seconds after the initial speed of 1.50 m/s downwards:
[tex]\begin{gathered} v_f=at+v_0 \\ =(-2.94\frac{m}{s^2})(4.00s)-1.5\frac{m}{s} \\ =-13.26\ldots\frac{m}{s} \\ \approx-13.3\frac{m}{s} \end{gathered}[/tex]Therefore, the answers are:
The acceleration of the elevator is 2.9 m/s^2 downwards.
The final speed of the elevator 4 seconds after it had a speed of 1.50 m/s downwards, is 13.3 m/s downwards.