Question

newton’s second and third laws of motion combined gravity is a force of attraction between objects that is due to their masses. an asteroid will fall to earth because gravity pulls the asteroid toward earth. this force is the action force exerted by earth’s gravity on the asteroid. but gravity also pulls earth toward the asteroid. this force is the reaction force exerted by the asteroid on earth. the effect of the action force is easy to see—the asteroid falls to earth. why do you not notice the effect of the reaction force—earth being pulled upward? newton’s third law says that when two objects interact, equal but opposite forces act on them. newton’s second law says that if the two objects have different masses, they will have different accelerations when acted on by the same force. in this example, the force acting on earth is equal to the force acting on the asteroid, but the mass of earth is much larger than the mass of the asteroid. therefore, the acceleration of earth due to this force is much smaller than the acceleration of the asteroid. action and reaction forces also occur when objects collide. imagine walking around a corner in a hallway and bumping into someone much larger than you. what happens to your motion compared to the other person’s motion? think of other examples in which two objects with different masses collide. how do newton’s laws of motion describe what happens after these collisions? 29. a particular bowling ball has a mass of 7 kg, and a standard bowling pin has a mass of 1.5 kg. use newton’s third law to describe what you expect to happen when the bowling ball collides with the pin. the ball applies an action force to the pin, and the pin applies an equal action / reaction force to the ball. the forces in this force pair act in the same direction / opposite directions. using newton’s second law, you know that the pin will accelerate more / less than the ball because it has less mass than the ball does.

Explanation:

To solve this, we analyze each blank using Newton's laws:

1. Newton’s third law states that for every action, there is an equal and opposite reaction. So the pin applies a reaction force to the ball (equal in magnitude to the action force from the ball).
2. Action - reaction force pairs act in opposite directions (they are mutual and opposite interactions).
3. Newton’s second law is \( F = ma \) (or \( a=\frac{F}{m} \)). Since the force \( F \) on both (from the action - reaction pair) is equal, and the pin has less mass (\( m_{\text{pin}}more than the ball.

Answer:

1. reaction
2. opposite directions
3. more