HELP ASAP TIMED TEST

A snowball is dropped from a height of H and reaches the ground with a speed of V. If you want to double the speed that the snowball has when it reaches the ground, at what height should you drop it from?

a
2H
b
4H
c
√2H

d
8H
e
16H

Answers

Answer 1

Answer:

Correct choice: b 4H

Explanation:

Conservation of the mechanical energy

The mechanical energy is the sum of the gravitational potential energy GPE (U) and the kinetic energy KE (K):

E = U + K

The GPE is calculated as:

U = mgh

And the kinetic energy is:

[tex]\displaystyle K=\frac{1}{2}mv^2[/tex]

Where:

m = mass of the object

g = gravitational acceleration

h = height of the object

v = speed at which the object moves

When the snowball is dropped from a height H, it has zero speed and therefore zero kinetic energy, thus the mechanical energy is:

[tex]U_1 = mgH[/tex]

When the snowball reaches the ground, the height is zero and the GPE is also zero, thus the mechanical energy is:

[tex]\displaystyle U_2=\frac{1}{2}mv^2[/tex]

Since the energy is conserved, U1=U2

[tex]\displaystyle mgH=\frac{1}{2}mv^2 \qquad\qquad [1][/tex]

For the speed to be double, we need to drop the snowball from a height H', and:

[tex]\displaystyle mgH'=\frac{1}{2}m(2v)^2[/tex]

Operating:

[tex]\displaystyle mgH'=4\frac{1}{2}m(v)^2 \qquad\qquad [2][/tex]

Dividing [2] by [1]

[tex]\displaystyle \frac{mgH'}{mgH}=\frac{4\frac{1}{2}m(v)^2}{\frac{1}{2}m(v)^2}[/tex]

Simplifying:

[tex]\displaystyle \frac{H'}{H}=4[/tex]

Thus:

H' = 4H

Correct choice: b 4H


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Which of these changes would likely occur if the rate of Earth's rotation on its axis decreased? The length of day would be shorter F The length of day would be longer G The length of the seasons would be shorter. H The length of the season would be longer.J

Answers

Answer:

F. The length of day would be longer

Explanation:

Earths rotates on its axis from the eastward to the westward direction, earth takes about 24 hours to complete its rotation. If the rate of earth's rotation on its axis slows down then  the days will be longer than usual.  Thought the length of year would remain the same. Earth rotation is also impacted by the sun and moon's gravitational pull. The disappearance of the centrifugal force form the surface would cause  climate changes and seasonal extremes.

A sheep is walking at 1.6 m/s. How long will it take to go 3600 m?

Answers

Answer:

2,250 seconds or 37.5 minutes

Explanation:

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Answer:

Explanation:

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Answer:

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Answer:

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When one wave crest overlaps the crest of another and they add together what happens to the amplitude?
A: stays the same
B: decreases
C: increases

Answers

I’d say the answer is “B”

When one wave crest overlaps with  the crest of another and they add together and their amplitude increases. Hence, C is correct.

What is amplitude ?

Amplitude of a wave is the distance from the midpoint of a crest to its top or the distance from the midpoint of a trough to its bottom. For a wave the peak to the top is called crest and peak to the bottom or decline is called troughs.

When two waves overlap by crest of one wave and trough of another wave, then their amplitude will decrease and it is called destructive interference.

Amplitude of a wave is directly related to its intensity. High amplitude waves are intense. When two waves overlaps by their crests and add up together their amplitude will be the sum of amplitudes of both waves. This is called constructive interference. Hence, option C is correct.

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EZ POINTS
20. An object's kinetic energy is a combination of its: A. mass and weight B. distance and direction C. mass and velocity D. volume and direction​

Answers

Answer:

A.

Explanation:

B,C,D is not right because those do not pay a factor on kinectic energy

What is solubility? (8th grade science)

Answers

the ability to be dissolved, especially in water.

What makes the eardrum vibrate?

Answers

Answer:

The sound waves are gathered by the outer ear and sent down the ear canal to the eardrum. The sound waves cause the eardrum to vibrate, which sets the three tiny bones in the middle ear into motion. The motion of the three bones causes the fluid in the inner ear, or cochlea, to move.

~+lil more info+~

The sound waves go through the ear canal into the middle ear, which includes the eardrum (a thin layer of tissue) and three tiny bones called ossicles. The sound causes the eardrum to vibrate. The ossicles amplify these vibrations and carry them to the inner ear.

When a 0.292 kg mass on a string is swung at 8.45 m/s, it feels a centripetal acceleration of 78.9 m/s^2. What is the radius of the swing? (Unit = m)

Answers

Answer:

0.905

Explanation:

right answer

The radius of the swing is 0.905 m

Circular motion

From the question, we are to determine the radius of the swing

Using the centripetal acceleration formula

[tex]a_{c}= \frac{v^{2} }{r}[/tex]

Where [tex]a_{c}[/tex] is the centripetal acceleration

v is the velocity

and r is the radius

From the given information,

v = 8.45 m/s

[tex]a_{c} = 78.9 \ m/s^{2}[/tex]

Then,

[tex]78.9 = \frac{8.45^{2} }{r}[/tex]

[tex]r = \frac{8.45^{2} }{78.9}[/tex]

[tex]r = \frac{71.4025}{78.9}[/tex]

r = 0.905 m

Hence, the radius of the swing is 0.905 m

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A student pulls horizontally on a block with a spring scale. The block reads 24.5 Newtons before the block starts to move. It reads 23.7 Newtons as she pulls the block at a constant velocity. How should she explain this?

Answers

Answer:

The coefficient of friction causes the force on the object to be less than its initial reading on the spring scale.

Explanation:

Since the block reads 24.5 N before the block starts to move, this is its weight. Now, when the block starts to move at a constant velocity, it experiences a frictional force which is equal to the force with which the student pulls.

Now, since the velocity is constant so, there is no acceleration and thus, the net force is zero.

Let F = force applied and f = frictional force = μN = μW where μ = coefficient of friction and N = normal force. The normal force also equals the weight of the object W.

Now, since F - f = ma and a = 0 where a = acceleration and m = mass of block,

F - f = m(0) = 0

F - f = 0

F = f

Since the force applied equals the frictional force, we have that

F =  μW and F = 23.7 N and W = 24.5 N

So, 23.7 N = μ(24.5 N)

μ = 23.7 N/24.5 N

μ = 0.97

Since μ = 0.97 < 1, the coefficient of friction causes the force on the object to be less than its initial reading on the spring scale.

A bicyclist with a mass of 50 kg is traveling at a rate of 30 m/s. It accelerates to a rate of 50 m/s in 5 seconds. What is the net force acting on the bicycle?

Answers

Answer:

200 N

Explanation:

There is only two needed factors in play here; the mass and acceleration

According to Newton's 2nd Law: F = m*a

Now Acceleration is Velocity over Time, so we have another factor in play: Acceleration = 50-30/5 = 20/5 = 4m/s^2

Net force = (50 kg)(4 m/s^2) = 50*4 = 200 Newtons

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Answers

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Answers

Electromagnetic waves or EM waves are waves that are created as a result of vibrations between an electric field and a magnetic field. ... They are hence known as 'electromagnetic' waves. The electric field and magnetic field of an electromagnetic wave are perpendicular (at right angles) to each other.

Hope this helps.
:)

A horizontal bar 1.5 metres long and of small cross-section rotates about vertical axis through one end. It accelerates uniformly from 1200 r.P.M. To 1500 r.P.M. In an interval of 5 seconds. What is the linear velocity at the beginning and end of the interval ? What are the normal and tangential components of the acceleration of the mid-point of the bar after 5 seconds after the acceleration begins ?

Answers

Answer:

a. i. 188.49 m/s. ii. 235.62 m/s. b. i. 117.81 m/s² ii. 4.71 m/s²

Explanation:

a. Since the linear velocity v = rω where r = radius of path = length of horizontal bar = 1.5 m and the initial angular speed ω₀ = 1200 r.P.M = 1200 × 2π/60 = 125.66 rad/s and final angular speed after the 5 seconds ω₁ = 1500 r.P.M = 1500 × 2π/60 = 157.08 rad/s

i. So, the initial linear velocity v₀ = rω₀ = 1.5 m × 125.66 rad/s = 188.49 m/s.

ii. The final linear velocity v₁ = rω₁ = 1.5 m × 157.08 rad/s = 235.62 m/s.

b. The mid-point of the bar is at a distance of one-half from the end of the bar. So its radius r' = r/2 = 1.5 m/2 = 0.75 m

i. Its normal acceleration a after the 5 seconds is a = r'ω₁² = 0.75 m × 157.08 rad/s = 117.81 m/s²

ii. Its tangential acceleration is given by a' = r'α where α = tangential acceleration

α = (ω₁ - ω₀)/t  where t = 5 seconds

α = (157.08 rad/s - 125.66 rad/s)/5 s

= 31.42 rad/s ÷ 5 s

= 6.28 rad/s²

a' = r'α

= 0.75 m × 6.28 rad/s²

= 4.71 m/s²

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Answers

Answer:4

Explanation:

If the velocity of an airplane is doubled, then its kinetic energy will increase by a factor of four.

What is kinetic energy?

The ability of an object to do work by virtue of its motion.

The kinetic energy is represented mathematically as

K.E = 1/2 mv²

where v is the velocity with which the object is moving and m is its mass.

When the velocity is doubled, kinetic energy is

K.E' = 1/2 m(2v)²

K.E' =4 x ( 1/2 mv²)

Thus,  airplane's kinetic energy will increase by a factor of four.

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Answers

Answer:

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Explanation:

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Answers

Answer:

Em are waves that are created as a result of vibrations between an electric field and a magnetic field.

Explanation:

Answer:

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Answers

Answer:

a = - 5 m/s²

Explanation:

The acceleration of the ball can be found by using the general formula of acceleration as follows:

[tex]a = \frac{\Delta V}{\Delta t}[/tex]

where,

a = acceleration of ball = ?

ΔV = change in velocity = Final Velocity - Initial Velocity

ΔV = - 0.4 m/s - 0.6 m/s = -1 m/s

Δt = time of contact with the wall = 0.2 s

Therefore, using the values in equation, we get:

[tex]a = \frac{-1\ m/s}{0.2\ s}\\\\a = -5\ m/s^2[/tex]

Therefore, the correct option is:

a = - 5 m/s²

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Answers

Answer:

These two forces are called action and reaction forces and are the subject of Newton's third law of motion. Formally stated, Newton's third law is: For every action, there is an equal and opposite reaction. The statement means that in every interaction, there is a pair of forces acting on the two interacting objects.

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Answer:

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Answer:

please try brainlist answer

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कृपया ब्रेनलिस्ट का उत्तर केवल 1more उत्तर देने का प्रयास करें।

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Answer:

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I GIVEING A !)) 100 point RIGHT NOW ASP

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Answer:

Constructed cladograms all typically share certain key features: Root – The initial ancestor common to all organisms within the cladogram (incoming line shows it originates from a larger clade) Nodes – Each node corresponds to a hypothetical common ancestor that speciated to give rise to two (or more) daughter taxa.

Explanation:

Answer:

one feature of a cladogram is a branch that shows you relations among animals

Explanation:

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Explanation:

sorry if wrong

Answer:

The answer is Desertification.

Explanation:

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Calculate its volume giving your answer to an appropriate
number of significant figures.

Answers

Answer:v=l x w x h

Explanation:

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l=length

Answer:

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Explanation:

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Answer:

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Explanation:

Answer:

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