Question

a rock is thrown straight up from the surface of the earth. which one of the following statements describes the energy transformation of the rock as it rises? neglect air resistance. a. the kinetic energy increases and the potential energy decreases. b. both the kinetic energy and the potential energy of the rock remain the same. c. the total energy of the rock increases. d. the kinetic energy decreases and the total energy of the rock increase. e. both the potential energy and the total energy of the rock increase.

Explanation:

When a rock is thrown straight up, its velocity decreases as it rises due to the gravitational - force acting against its motion. Kinetic energy ($K = \frac{1}{2}mv^{2}$) depends on velocity. As velocity $v$ decreases, kinetic energy decreases. Gravitational potential energy ($U = mgh$) increases as the height $h$ of the rock above the Earth's surface increases. In the absence of air - resistance, the total mechanical energy ($E=K + U$) is conserved.

Answer:

None of the above options are correct. The correct statement is that the kinetic energy decreases and the potential energy increases while the total energy remains the same.