Which of the following statements applies to the motion of a ball rising and then falling in free fall?
i. the ball has constant acceleration as it moves upward.
ii. the ball has constant acceleration at the top of its path.
iii. the ball has constant acceleration as it moves downward.

An engineer designs a roller coaster so that a car travels horizontally for 162 ft, then climbs 127 ft at an angle of 31.0° above the horizontal. it then moves 127 ft at an angle of 46.0° below the horizontal. if we take the initial horizontal motion of the car to be along the +x-axis, what is the car's displacement? (give the magnitude of your answer, in ft, to at least four significant figures and give the direction of your answer in degrees counterclockwise from the +x-axis.)

The total amount of energy contained in an object

Which planet do you think would be easiest for humans to colonize some day?