Carter has a mass of 120 kilograms. Riley has a mass of 54 kilograms. Riley is running with a football down the field at a speed of 7 meters per second. Carter collides with Riley at a velocity that consists of the same speed and opposite direction.

Question

Which selection best describes the results?

A
Riley will experience a change in his velocity; his speed will increase in the same direction he was moving as a result of the collision with Carter.
B
Carter will experience a change in his mass; he will lose 66 kg of mass as a result of the collision with Riley.
C
Riley will experience a change in his velocity; he will move in a direction opposite the way he was moving before the collision with Carter.
D
Riley will experience no change in velocity.

Answer 1

In this scenario, we have two individuals colliding: Riley, who has a mass of 54 kg and is running at 7 m/s, and Carter, who has a mass of 120 kg and is moving towards Riley at a speed of 7 m/s (opposite direction).

To analyze the results of the collision, we can apply the principles of conservation of momentum. Since both individuals have the same speed but in opposite directions, the momentum before the collision can be considered.

1. Calculate the momentum before the collision:

   • Momentum of Riley = mass × velocity = 54 kg × 7 m/s = 378 kg·m/s (in one direction)
   • Momentum of Carter (moving in the opposite direction) = mass × velocity = 120 kg × (-7 m/s) = -840 kg·m/s

2. The total momentum before the collision:

   • Total momentum = 378 kg·m/s + (-840 kg·m/s) = -462 kg·m/s

Since the total momentum is not zero, and momentum is conserved, we can expect a significant change in velocities upon collision.

Analyzing the options:

• A: Riley will experience a change in his velocity; his speed will increase in the same direction he was moving as a result of the collision with Carter. This is unlikely because Carter has a much greater mass, meaning it's more likely Riley will be influenced to reverse direction rather than increase speed in the same direction.

• B: Carter will experience a change in his mass; he will lose 66 kg of mass as a result of the collision with Riley. This is incorrect; mass does not change as a result of a collision.

• C: Riley will experience a change in his velocity; he will move in a direction opposite the way he was moving before the collision with Carter. This option is likely true because Carter's mass is significantly larger, so he is likely to push Riley back in the opposite direction.

• D: Riley will experience no change in velocity. This is not true because the collision is occurring, and both players will have their velocities affected.

Based on this analysis, the best selection that describes the results is:

C: Riley will experience a change in his velocity; he will move in a direction opposite the way he was moving before the collision with Carter.