Is work being done on a barbell when a weight lifter is holding the barbell
over his head?

Answer:

9J

Explanation:

Given parameters:

Mass of cell phone  = 80g

          1000g  = 1kg

            80g is therefore 0.08kg

Velocity of the cellphone  = 15m/s

Unknown:

Kinetic energy of the cellphone  = ?

Solution:

The kinetic energy of a body is the energy due to its motion.    

 It is expressed as:

    K.E  = [tex]\frac{1}{2}[/tex] mv²   =  [tex]\frac{1}{2}[/tex]  x 0.08 x 15²   = 9J

Answer: I believe the correct answer is A.

Answer:

2.5m/s²

Explanation:

Given parameters:

Mass of car  = 1400kg

Resultant force  = 3500N

Speed  = 30m/s

Unknown:

Average acceleration = ?

Solution:

According to the Newton's second law of motion:

     Force  = mass x acceleration

Now;

       3500 = 1400 x acceleration

      Acceleration  = [tex]\frac{3500}{1400}[/tex]   = 2.5m/s²

Answer:

[tex]\boxed {\boxed {\sf 12 \ Newtons }}[/tex]

Explanation:

Force is equal to the product of mass and acceleration.

[tex]F=m*a[/tex]

We know the mass, but not the acceleration. Therefore, we must calculate it before we can calculate force.

1. Calculate Acceleration

Acceleration is the change in velocity over the change in time.

[tex]a=\frac{V_f-V_i}{t}[/tex]

The final velocity is 10 meters per second and the initial velocity is 4 meters per second. The time is 1 second.

[tex]V_f=10 \ m/s \\V_i= 4 \ m/s \\t= 1 \ s[/tex]

Substitute the values into the formula.

[tex]a=\frac{10 \ m/s-4 \ m/s }{1 \ s}[/tex]

Solve the numerator.

[tex]a=\frac{6 \ m/s}{1 \ s }[/tex]

Divide.

[tex]a= 6 \ m/s/s=6 \ m/s^2[/tex]

2. Calculate Force

Now we know the acceleration and the mass.

[tex]m= 2 \ kg \\a= 6 \ m/s^2[/tex]

Substitute the values into the fore formula.

[tex]F= 2 \ kg * 6 \ m/s^2[/tex]

Multiply.

[tex]F= 12 \ kg*m/s^2[/tex]

[tex]F= 12 \ N[/tex]

The force applies to the ball was 12 Newtons.

Answer:

I guess that the atoms are:

Protons:     6     8    5    2    12    12

Neutrons:  8     8     5   3     13    14

Now, two atoms are isotopes if they share the same number of protons (so both atoms are the same element) but they have a different number of neutrons.

From the given options, the only two that have the same number of protons but a different number of neutrons are:

Protons 12, neutrons 13

and

Protons 12, neutrons 14.

These two are isiotopes.

Answer:

20 Hz, 20000 Hz

0.0166 m, 16.6 m

Explanation:

The minimum frequency that a human ear can hear is 20 Hz

The maximum frequency that a human ear can hear is 20000 Hz.

v = Velocity of sound = 332 m/s

Wavelength is given by

[tex]\lambda=\dfrac{v}{f}\\\Rightarrow \lambda=\dfrac{332}{20}\\\Rightarrow \lambda=16.6\ \text{m}[/tex]

The longest wavelength that can be heard by the human ear is 16.6 m

[tex]\lambda=\dfrac{332}{20000}\\\Rightarrow \lambda=0.0166\ \text{m}[/tex]

The shortest wavelength that can be heard by the human ear is 0.0166 m.

The experimental group and treatment group are the same group. It's just two different names for the same thing. If you apply a treatment to a group, then that's where you're performing the experiment.

For instance, if you are testing a fertilizer, then the independent variable would be "use of fertilizer or not using fertilizer". So that means the control group doesn't get any fertilizer. The dependent variable would be the heights of the plants between the two groups, so we can see if the fertilizer has an effect or not. This is the result of the experiment. So in other words, the input is the fertilizer (or no fertilizer), and the output is measuring the heights of the plants. The output is the result we analyze.

Keep in mind that the heights of the plants are likely to be randomly distributed. So this is where statistics comes into play. If the plants grow due to some random chance, and not necessarily the fertilizer, then you can use the control group to determine if that's the case or not. The control group helps you do this comparison.

As the name implies, "dependent" means it relies on something else. The height of the plant relies on if you used fertilizer or not. The independent variable is able to change without relying on any other variable.

Resistance is a material's tendency to resist the flow of charge (current). Resistance is the measure of the opposition to motion of free electrons(current) due to their continuous collisions with the atom of the lattice. An electric current flows when electrons move through a conductor, such as a metal wire. The moving electrons can collide with the atoms in the metal. This makes it more difficult for the current to flow, and causes resistance. The unit of Resistance is "OHM". Ohm is denoted by the greek letter "Ω".

  If a current 'I' is caused to flow in a conductor by a battery of potential difference 'V', it is found that the current is directly proportional to potential difference provided there is no change in the conductor itself. That means more will be I if we increase V. So

                     [tex]{\Longrightarrow}\qquad \qquad \qquad I {\propto} V\\\\{\Longrightarrow}\qquad \qquad \qquad I = KV[/tex]

Where K is Conductance. Conductance is the ability of a conductor to allow the current to pass through it.  Resistance(R) is the reciprocal(opposite) of conductance(K) thus K is inversely proportional to R,

                     [tex]{\Longrightarrow}\qquad \qquad \qquad I = \frac{1}{R}V \\\\{\Longrightarrow}\qquad \qquad \qquad V = IR[/tex]

This is known as OHM's Law, and V = IR is the equation linking the R, V and I.

[tex]\Huge\text{Circuit Diagram:}[/tex]

Circuit Diagram no 1 attached is of this question. In the circuit diagram, V is voltmeter to find the potential difference, A is the ammeter to find the current, R is the resistance i.e. the conductor wire, The switch and the battery.

Suppose the wire of length 100 cm is connected to a battery, the Voltmeter observes the potential difference and ammeter reads the current of the wire. We will use the R, V and I i.e. V = IR equation to find out the resistance of that wire and Record the resistance. Then attach another small wire of suppose 90 cm to the battery, and similarly Find out its resistance too. After recording the resistance 3 or 4 times, you will observe that When you decrease the length of the wire,

The resistance of a conductor depends upon the following factors.

                   [tex]{\Longrightarrow}\qquad \qquad \qquad R\quad {\propto}\quad L[/tex]    

                   [tex]{\Longrightarrow}\qquad \qquad \qquad R\quad {\propto}\quad \frac{1}{A}[/tex]

The relation between only length of the wire and resistance is [tex]R\quad {\propto} \quad L[/tex] . The relation of R, L and A is given by, ρ

                    [tex]{\Longrightarrow}\qquad \qquad \qquad R\quad {\propto}\quad \frac{L}{A}\\\\{\Longrightarrow}\qquad \qquad \qquad R\quad =\ \frac{\ {\rho}\ L\ }{A}[/tex]

Where ρ is known as resistivity depends upon the nature of the material of the wire. The meter of resistivity is Ω x m(Ohm x meter).

[tex]\Huge\text{I-V Characteristic:}[/tex]

I-V curves of an electrical device or component, are a set of graphical curves which are used to define its operation within an electrical circuit. I-V characteristic curves show the relationship between the current flowing through an electronic device and the applied voltage across its terminals. The circuit diagram to find I-V characteristic must have a resistor which is a device or component connected to a battery which is providing the potential difference V. When a resistor is connected to a battery, current I is observed due to drift velocity. To find the current and potential difference(voltage) the circuit must have the Ammeter and voltmeter. Recorded current and voltage must be used to plot the graph to check the I-V characteristic. The picture attached is the circuit diagram.

We calculate the resistance at constant temperature by ohm's law. The Ohms law is applied at constant temperature because the resistance of any material varies with the change in temperature. It shows a linear relationship between the applied voltage and the resulting current, resistance being a constant. So we could use V = IR because resistance is constant at constant temperature.

Answer:

c

Explanation:

speed=distance÷time

40÷10=4

0.184[tex]m^{3}[/tex] is the answer for Acellus students!

None can.

A clinical thermometer only measures temperatures above +30°C.

Mercury and alcohol are both frozen solid at -50°C.

Answer:

Objects; waves.

Explanation:

Waves interact with objects and other waves. Thus, waves are used on objects such as mobile phones and can be transformed from one form to another.

There are various types of waves in our physical environment such as gamma rays, x-rays, ultraviolet waves, radio waves etc.

Radio waves can be defined as an electromagnetic wave that has its frequency ranging from 30 GHz to 300 GHz and its wavelength between 1mm and 3000m. Therefore, radio waves are a series of repetitive valleys and peaks that are typically characterized of having the longest wavelength in the electromagnetic spectrum.

Basically, as a result of radio waves having long wavelengths, they are mainly used in long-distance communications such as the carriage and transmission of data. Some examples of communication technologies that uses radio waves are radio set, mobile phones, television etc.

Answer:

I think it is A or B, but more B as for John used 20 more net force. I recommend doing some research, sorry.

Answer:

I think the answer is B, I may be wrong...

Explanation:

Answer: I think Windows.

Explanation: The absorption of light makes an object dark or opaque to the wavelengths or colors of the incoming wave: Wood is opaque to visible light. Some materials are opaque to some wavelengths of light, but transparent to others. Glass and water are opaque to ultraviolet light, but transparent to visible light.

Option.D-All materials is the correct answer.
Any object, whether living or inert, has the ability to absorb light. Absorption is always influenced by the electromagnetic frequency of the light being transmitted (i.e., its color) and the composition of the object's atoms.

To learn more Absorption of a light, click here-
https://brainly.com/question/26655381

#SPJ2

Answer:

It's closest to 3 degrees celsius

Explanation:

For this use the formula:

d = Vo * t - (at^2) / 2

Clearing t:

t = d/(v + 0.5*a)

Replacing:

t = 5 m / (7.2 m/s + 0.5 * (-1.1 m/s²)

Resolving:

t = 5 m / (7.2 m/s + (-0.55 m/s²)

t = 5 m / 6.65 m/s

t = 0.75 s

Result:

The time will be 0.75 seconds.

Answer: Optical test is a test which is used to assess vision and ability of the person to focus on the objects.

Explanation:

The following are the advantages of utilizing plane mirror in optical testing:

1. When a plane mirror is used for testing the image of the test card must be placed at distance equal to the distance of the object.  

2. Larger distance in between the object or test card and viewer is obtained. This can help in determining the exact ability of the eye to focus on objects.

Answer:

An electromagnet is a magnet that runs on electricity. Unlike a permanent magnet, the strength of an electromagnet can easily be changed by changing the amount of electric current that flows through it. The poles of an electromagnet can even be reversed by reversing the flow of electricity.

Answer:

[tex]V_{B/A}=2i+2k[/tex]

Explanation:

The relative velocity can be calculated by means of the difference between vector B minus vector A.

[tex]V_{A}=i+2j-3k\\V_{B}=3i+2j-k\\V_{B}-V_{A}=(3-1)i + (2-2)j+(-1-(-3))k\\V_{B/A}=2i+2k[/tex]

Answer:

The mass of the squirrel is 0.51kg

A squirrel runs at a speed of 9.9 m/s with 25 J of kinetic energy.

What is the squirrel’s mass?

Answer: 0.51 kg

We are given:

Mass of object 1(m₁) = 3000 kg

Mass of object 2(m₂) = 4500 kg

Distance between their centers(r) = 1.5 m

Gravitational Attraction between the objects:

We know the formula:

g = G(m₁)(m₂) / r² ,where G is the universal Gravitational Constant and g is the force of attraction

g = (6.67 * 10⁻¹¹ * 3 * 10³ * 4.5 * 10³) / (1.5)²

g = [(6.67 * 3 * 4.5) * (10³⁺³⁻¹¹)] / 2.25

g = (90 * 10⁻⁵) / 2.25

g = 40 * 10⁻⁵ N

Answer:

Free body diagram

Explanation:

A free body diagram shows all the forces acting on a body. Since force is a vector quantity, the magnitude and direction of the forces are shown in the free-body diagram.

Force is the push or pull on a body.

It can be via contact or without contact. Such non-contact forces acts via a force field.

In physics, this free body diagram is used extensively.

Answer:

Gravity creates stars and planets by pulling together the material from which they are made.

Explanation: Thats the only thing i have im stuck on the tga quiz

Explanation:

what is time in this question

Answer:

930 centimeters

Explanation:

Answer:

Approximately [tex]5.5\; \rm N[/tex], assuming that the volume of these two charged objects is negligible.

Explanation:

Assume that the dimensions of these two charged objects is much smaller than the distance between them. Hence, Coulomb's Law would give a good estimate of the electrostatic force between these two objects regardless of their exact shapes.

Let [tex]q_1[/tex] and [tex]q_2[/tex] denote the magnitude of two point charges (where the volume of both charged object is negligible.) In this question, [tex]q_1 = 20 \times 10^{-6}\; \rm C[/tex]  and [tex]q_2 = 15 \times 10^{-6}\; \rm C[/tex].

Let [tex]r[/tex] denote the distance between these two point charges. In this question, [tex]r = 0.7\; \rm m[/tex].

Let [tex]k[/tex] denote the Coulomb constant. In standard units, [tex]k \approx 8.98755\times 10^{9}\; \rm kg \cdot m^{3}\cdot s^{-2}\cdot C^{-2}[/tex].

By Coulomb's Law, the magnitude of electrostatic force (electric force) between these two point charges would be:

[tex]\begin{aligned}F &= \frac{k \cdot q_1 \cdot q_2}{r^{2}}\end{aligned}[/tex].

Substitute in the values and evaluate:

[tex]\begin{aligned}F &= \frac{k \cdot q_1 \cdot q_2}{r^{2}}\\ &\approx 8.98755 \times 10^{9}\; \rm kg \cdot m^{3}\cdot s^{-2}\cdot C^{-2} \\ &\quad \times 20\times 10^{-6}\; \rm C\\ &\quad \times 15\times 10^{-6}\; \rm C \\ &\quad \times \frac{1}{{(0.7\; \rm m)}^{2}}\\ &\approx 5.5\; \rm N \end{aligned}[/tex].

Answer:

73.72

Explanation:

For this subtraction problem, the answer or solution is expressed to the least precise of the numbers we are trying to subtract.

The least precise number is the number with the lowest significant numbers:

105.4 - 31.681

105.4  has 4 significant numbers

31.681 has 5 significant numbers

  So;

             105.4  

        -      31.681

        ------------------

                 73.719

          ----------------

The solution is therefore  73.72