A block of \(1\) kg is released from the top of a smooth curve \(\mathrm{AB},\) and then it encounters a rough surface \(\mathrm{BC},\) coming to rest at \(\mathrm{C}.\) The work done by friction is:
(take \(g=10\) m/s2)
           
1. \(25\) J
2. \(50\) J
3. \(-25\) J
4. \(-50\) J

Subtopic:  Work Energy Theorem |
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The work done by all the forces (external and internal) on a system equals the change in:

1. total energy 2. kinetic energy
3. potential energy 4. none of these
Subtopic:  Work Energy Theorem |
 73%
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A bullet from a gun is fired on a rectangular wooden block with velocity \(u\). When bullet travels \(24\) cm through the block along its length horizontally, velocity of bullet becomes \(u/3\). Then it further penetrates into the block in the same direction before coming to rest exactly at the other end of the block. The total length of the block is:
1. \(30\) cm
2. \(27\) cm
3. \(24\) cm
4. \(28\) cm
Subtopic:  Work Energy Theorem |
 67%
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NEET - 2023
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A body of mass \(1\) kg is thrown upwards with a velocity \(20\) ms-1. It momentarily comes to rest after attaining a height of \(18\) m. How much energy is lost due to air friction?
(Take \(g=10\) ms-2)
1. \(20\) J
2. \(30\) J
3. \(40\) J
4. \(10\) J

Subtopic:  Work Energy Theorem |
 87%
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AIPMT - 2009
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In a ballistics demonstration, a police officer fires a bullet of mass \(50.0\) g with speed \(200\) m/s on soft plywood of thickness \(2.00\) cm. The bullet emerges with only \(\text{10%}\) of its initial kinetic energy. The emergent speed of the bullet is:
1. \(0\)
2. \(53.2\) m/s
3. \(63.2\) m/s
4. \(6.32\) m/s

Subtopic:  Work Energy Theorem |
 66%
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