Physics
A skater is gliding on a smooth ice surface. What happens to his mechanical energy as he skates?
- It increases
- It decreases
- It becomes zero
- It remains constant
Work, Energy & Power
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Answer
It remains constant
Reason — As the skater glides across the ice, he possess kinetic energy due to his movement. The potential energy remains constant as there is no significant change in height. Assuming a smooth ice surface with no friction or air resistance, the external forces are absent, hence, according to the principle of conservation of mechanical energy, the total mechanical energy (KE + PE) of the skater remains constant.
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Related Questions
A spring is kept compressed by a small trolley of mass 0.5 kg lying on a smooth horizontal surface as shown. When the trolley is released, it is found to move at a speed of v = 2 ms-1. What potential energy did the spring possess when compressed?
According to the principle of conservation of mechanical energy :
- Potential energy of a system is always greater than its kinetic energy
- Kinetic energy of a system is always greater than its potential energy
- Mechanical energy is always converted into heat energy
- Total mechanical energy of a system remains constant if no external force is worked on it.
A spring is compressed storing potential energy. When the spring is released it propels an object forward. What change would you notice in the total mechanical energy of the system?
- It increases
- It decreases
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A ball of mass m is thrown vertically up with an initial velocity so as to reach a height h. The correct statement is:
- Potential energy of the ball at the ground is mgh.
- Kinetic energy of the ball at the ground is zero.
- Kinetic energy of the ball at the highest point is mgh.
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