Question

26.
after
before
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

1. 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:

To determine in which crash the cone experienced a stronger force, we use Newton's third law (action - reaction) and the concept of force and acceleration (F = ma, where F is force, m is mass, and a is acceleration). In Crash 1, the black puck (more mass) sped up by 8 m/s. In Crash 2, the blue puck (less mass) sped up by 4 m/s. The force on the puck is F = mΔv/Δt (assuming same time interval for the crash). For the black puck, with more mass and a larger change in velocity, the force on the puck is stronger. By Newton's third law, the force the puck exerts on the cone (and vice versa) is equal in magnitude and opposite in direction. So a stronger force on the puck means a stronger force on the cone. Option a is wrong because there must be a force on the cone due to the crash. Option b is wrong as we can infer from the puck's motion. Option c is wrong as the change in speed and mass of the pucks are different, so forces are different. Option d is correct as the black puck (more mass, larger speed change) has a stronger force, so the cone in Crash 1 has a stronger force.

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.