Author Question: A 3.0-kg mass is dropped from the edge of a 50-m tall building with an initial speed of zero. The ... (Read 127 times)

ghost! · **on:** Jul 28, 2018

A 3.0-kg mass is dropped from the edge of a 50-m tall building with an initial speed of zero. The mass strikes the ground with a downward velocity of 25 m/s. Find the change in mechanical energy of the mass caused by air resistance between the point where it is dropped and the point where it strikes the ground?
a. -0.46 kJ
b. -0.53 kJ
c. -0.61 kJ
d. -0.38 kJ
e. -0.81 kJ

Question 2

A particle is acted upon by only two forces, one conservative and one nonconservative and neither being a force of friction, as it moves from point A to point B. The kinetic energies of the particle at points A and B are equal if
a. the sum of the works of the two forces is zero.
b. the work of the conservative force is equal to the work of the nonconservative force. c. the work of the conservative force is zero.
d. the work of the nonconservative force is zero.
e. None of the above.