When work done by force of gravity is negative (only gravity is acting)
Correct answer: C. Both (A) and (B)
- A. KE decreases
- B. PE increases
- C. Both (A) and (B)
- D. None of these
Explanation
If the work done by gravity is negative, it means that the gravitational force is acting in the direction opposite to the direction of motion of the object. In this case, the kinetic energy of the object decreases, since the force of gravity is slowing it down. At the same time, the potential energy of the object increases, since it is moving towards a higher position in the gravitational field.For example, if a ball is thrown upwards, the work done by gravity is negative as it is acting in the opposite direction of the motion of the ball. As the ball moves upwards, its kinetic energy decreases, and its potential energy increases. At the highest point of the trajectory, the kinetic energy of the ball is zero, and all its initial kinetic energy has been converted into potential energy.
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About Work-Energy Theorem
The work-energy theorem states that the net work done on an object equals its change in kinetic energy. Questions involve positive and negative work, variable forces and force-displacement graphs, acceleration or deceleration, and the difference between this theorem and conservation of mechanical energy, which also requires attention to potential energy and non-conservative work.
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