Question

mateo and jackie were on a playground rolling some different - sized balls to get them to crash. they used a tennis ball (the same mass) in both crashes. they tried two soccer balls - a pink one (more mass) for crash 1 and a blue one (less mass) for crash 2. mateo and jackie want to know what happened to the tennis ball. use information from the diagram to answer. in which crash did the tennis ball experience a stronger force? how do you know? a. crash 1; the force on the soccer ball was stronger in this crash, so the force on the tennis ball was also stronger. b. there was no force on the tennis ball. in each crash only the soccer ball experienced a force. c. it was the same in both crashes. the soccer ball changed speed by the same amount in each crash, so the force on the tennis ball was the same both times. d. the diagram doesnt tell you anything about the force on the tennis ball. it only gives information about the force on the soccer balls.

Explanation:

To determine in which crash the tennis ball experienced a stronger force, we use Newton's third law (action - reaction) and the concept of force and acceleration ($F = ma$). In Crash 1, the pink soccer ball (more mass) had a speed change. In Crash 2, the blue soccer ball (less mass) had a speed change. The force on the soccer ball is $F = m\Delta v / \Delta t$ (assuming time of collision is similar). For Crash 1, the pink ball (more mass) had a $\Delta v$ (from 12 m/s to 15 m/s, $\Delta v=3$ m/s) and more mass, so the force on the soccer ball is larger. By Newton's third law, the force on the tennis ball (action - reaction pair) is equal in magnitude to the force on the soccer ball. So in Crash 1, the force on the tennis ball is stronger. Option a correctly states this as it says the force on the soccer ball was stronger in Crash 1, so the force on the tennis ball (action - reaction) was also stronger. Option b is wrong as collisions involve forces on both objects. Option c is wrong as the soccer balls have different masses, so same $\Delta v$ doesn't mean same force. Option d is wrong as we can infer from the soccer ball's motion (mass and speed change) about the force on the tennis ball.

Answer:

a. Crash 1; the force on the soccer ball was stronger in this crash, so the force on the tennis ball was also stronger.