Question

work, energy, power tf review
a. the total amount of mechanical energy of an object is the sum of its potential energy and the kinetic energy.
b. heat is a form of mechanical energy.
c. the mechanical energy of an object is always conserved.
d. when forces do work, energy may be transformed from kinetic to potential (or vice versa), but the total mechanical energy is always conserved.
e. a bowling ball is mounted from a ceiling by way of a strong cable. it is drawn back and released, allowed to swing as a pendulum. as it swings from its highest position to its lowest position, the total mechanical energy is mostly conserved.
f. when a friction force does work on an object, the total mechanical energy of that object is changed.
g. when energy is \lost\ it is usually only transferred to a non - mechanical form.
h. because of the second law of thermodynamics, no machine is 100% efficient.

Explanation:

A. Mechanical energy is defined as the sum of potential and kinetic energy.
B. Heat is thermal energy, not mechanical (mechanical = potential + kinetic).
C. Mechanical energy is conserved only if no non-conservative forces (e.g., friction) act.
D. Work by non-conservative forces changes total mechanical energy; only conservative forces preserve it.
E. A pendulum with minimal air resistance has mostly conserved mechanical energy (PE ↔ KE).
F. Friction (non-conservative) does work, converting mechanical energy to heat, changing total mechanical energy.
G. "Lost" energy is transferred to non-mechanical forms (e.g., heat, sound), not destroyed.
H. The second law of thermodynamics states energy degrades to less useful forms, so no machine is 100% efficient.

Answer:

A. True
B. False
C. False
D. False
E. True
F. True
G. True
H. True