Question

force and motion end - of - unit assessment (continued)
before after
crash 1

black puck: more mass
moving 8 m/s
black puck: moving 12 m/s
(sped up by 4 m/s)
crash 2

blue puck: less mass
moving 8 m/s
blue puck: moving 12 m/s
(sped up by 4 m/s)

1. after hockey practice, carissa and keenan were playing a game where they were pushing some objects to get them to crash. they were using a cone and two different pucks - a black one with more mass for crash 1 and a blue one with less mass for crash 2. they want to know what happened to the cone. use the information from the diagram to answer.

in which crash did the cone experience a stronger force? how do you know?
a. there was no force on the cone. in both crashes, only the hockey puck experienced a force.
b. the diagram doesnt tell you anything about the force on the cone. it only gives information about the force on the pucks.
c. it was the same force in both crashes; the hockey puck changed speed by the same amount in each crash, so the force on the cone was the same each time.
d. crash 1; the force on the black hockey puck was stronger in this crash, so the force on the cone was also stronger.

Explanation:

According to Newton's third law of motion, when two objects interact, the forces they exert on each other are equal in magnitude and opposite in direction. In Crash 1, the black puck (with more mass) had a greater change in motion (speed increased by 4 m/s). Since force is related to the change in motion (and mass), a stronger force was exerted on the black puck in Crash 1. By Newton's third law, the force on the cone (which exerted the force on the puck) is equal in magnitude to the force on the puck. So, the force on the cone in Crash 1 is stronger.

Answer:

d. Crash 1; the force on the black hockey puck was stronger in this crash, so the force on the cone was also stronger.