Question

As the block slides across the floor, what happens to its kinetic energy K, potential energy U, and total mechanical energy E ?

a. K decreases; U increases; E decreases
b. K increases; U decreases; E decreases
c. K decreases; U stays the same; E decreases
d. K increases; U stays the same; E decreases
e. K decreases; U increases; E stays the same
f. K increases; U decreases; E stays the same

Answer 1

The kinetic energy of the block decreases due to friction, potential energy remains the same on a level floor, and total mechanical energy decreases as energy is lost to heat.

Step-by-step explanation:

As a block slides across the floor, its kinetic energy (K) typically decreases due to friction acting opposite to the motion, converting some of that energy into heat. The potential energy (U) of the block, assuming the floor is level, would stay the same as there is no change in altitude or configuration that would affect its potential energy. The total mechanical energy (E) of the block would decrease since some of the kinetic energy is being lost to friction and not being converted into potential energy.

Therefore, the correct answer is: K decreases; U stays the same; E decreases. This accounts for the loss of mechanical energy due to non-conservative forces such as friction, which is common in real-world scenarios where energy is not conserved due to energy transitions to non-mechanical forms like heat.