Efficiency is ?
a. the percentage of energy lost to the surrounding as heat.
b. the percentage of energy that is actually used to perform work.
c. the entire amount of energy.
d. the time it takes for half of the energy to be used.

An equinox occurs when a. neither end of earth's axis is tilted toward or away from the sun. b. the north end of earth's axis is tilted away from the sun. c. the north end of earth's axis is tilted toward the sun. d. earth's axis is parallel to the sun's rays. select the best answer from the choices provided a b c d

When considering gravity acceleration and the force of acceleration, what must be true? a. the direction of acceleration must be perpendicular to the direction of the force. b. the direction of the force and the direction of acceleration must be the same as each other. c. the direction of the force and the direction of acceleration must be opposite of each other. d. the mass of the body must be the same as the acceleration of the body.

The free body diagram shows a box being pulled to the left up a 25-degree incline. the magnitude of the normal force is