Question

1. energy is the ability to *

eat
do work
to change forms
nothing

1. the gravitational pull is greater between two objects that *

are farther apart.
have rougher surfaces.
are moving at greater speed
have greater masses.

1. three chairs were rolling across a flat office floor. the blue and red chairs are the same mass, and they have more mass than the yellow chair. each chair was hit by another chair, but not from the same direction. use the information in the diagram to answer. which chair(s) experienced the strongest force when hit? how do you know?

Explanation:

• Question 8: Energy is defined as the ability to do work. The option "to change forms" is a property of energy (like energy can change from one form to another, e.g., potential to kinetic), but the fundamental definition is about work - doing. "Eat" and "nothing" are incorrect.
• Question 9: According to Newton's law of universal gravitation \(F = G\frac{m_1m_2}{r^2}\), where \(F\) is the gravitational force, \(G\) is the gravitational constant, \(m_1\) and \(m_2\) are the masses of the two objects, and \(r\) is the distance between their centers of mass. The gravitational pull is directly proportional to the product of the masses (\(m_1m_2\)) and inversely proportional to the square of the distance (\(r^2\)). "Are farther apart" would decrease the force, "have rougher surfaces" is related to friction (not gravity), and "are moving at greater speed" is related to kinetic energy (not the gravitational pull formula).

Answer:

• Question 8: B. do work
• Question 9: D. have greater masses