Question

If the speed of a car is halved, how does its kinetic energy change?

April 18, 2024

Answer

Let speed of car be v.

Kinetic Energy at speed v = $1\over 2$ × m × v²

= ${1\over 2}mv^2$

Kinetic Energy at speed v = $1\over 2$ × m × ( $v\over 2$ )²

= ${1\over 8}mv^2$

= ${1\over 4}{mv^2\over 2}$

Hence, when the speed of the car is halved the kinetic energy becomes one-fourth.

💡 Some Related Questions

The figure alongside shows a simple pendulum of mass 200 g. It is displaced from the mean position A to the extreme position B. The potential energy at position A is zero. At position B the bob is raised by 5 m.
(a) What is the potential energy of the pendulum at position B ?
(b) What is the total mechanical energy at point C?
(c) What is the speed of the bob at position A when released from position B ? (Take g = 10 ms^-2)

The bob of a simple pendulum is imparted a velocity of 5 m s^-1 when it is at its mean position. To what maximum vertical height will it rise on reaching at its extreme position if 60% of its energy is lost in overcoming the friction of air? (Take g = 10 m s^-2).

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(a) Calculate the change in the gravitational potential energy of the skier between A and B.
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(Take g = 10 ms^-2).

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(c) What happens to the mechanical energy after the ball hits the ground and comes to rest?

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Calculate:
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(b) the kinetic energy on reaching the ground
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(iii) the body has reached the ground.

Name the type of energy possessed by the bob of a simple pendulum when it is at
(a) the extreme position,
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(c) between the mean and extreme positions.