Physics
A block slides down a frictionless incline. The sum of its P.E. and K.E. at every point :
- increases
- decreases
- remains constant
- first decreases and then increases
Work, Energy & Power
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Answer
remains constant
Reason — When a block slides down a frictionless incline, no energy is lost due to friction. The gravitational potential energy decreases as the block moves downward, while its kinetic energy increases by the same amount. Therefore, the sum of potential energy and kinetic energy (mechanical energy) remains constant throughout the motion.
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Related Questions
A pendulum is oscillating on either side of its rest position. The correct statement is :
- It has only the kinetic energy at its each position.
- It has the maximum kinetic energy at its extreme position.
- It has the maximum potential energy at its mean position.
- The sum of its kinetic energy and potential energy remains constant throughout the motion.
A simple pendulum while oscillating rises to a maximum vertical height of 7 cm from its rest position where it reaches its extreme position on one side. The mass of the bob of simple pendulum is 400 g and g = 10 m/s2. The total energy of the simple pendulum at any instant while oscillating is:
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- 28 J
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Which of the following is not an example of conservation of mechanical energy :
- free fall
- ideal pendulum
- block sliding down a rough surface
- satellite orbiting the earth
Assertion (A): When a hammer is made to fall on a nail fixed upright on a wooden piece, the nail begins to penetrate the wood.
Reason (R): As the hammer starts falling, its kinetic energy begins to change into potential energy.
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true and R is not the correct explanation of A.
- assertion is false but reason is true.
- assertion is true but reason is false.