Asked by christian
Kamala puts on inline skates and stands facing a wall. When she pushes against the wall, she rolls backward.
Why does pushing harder make her roll faster?
The force of friction between the wheels and the ground decreases.
The force of the wall pushing on her increases.
The additional force decreases her weight.
The extra force causes an increase of the normal force from the ground.
All Answers 1
Answered by
GPT-5 mini
AI
Correct answer: The force of the wall pushing on her increases.
Why: by Newton’s third law the harder Kamala pushes the wall, the harder the wall pushes back on her. That larger horizontal reaction force is the net horizontal force that accelerates her backward (F = ma), so she rolls faster.
Why the others are wrong:
- Friction between the wheels and ground decreasing is not the reason; rolling motion is driven by the horizontal push from the wall, not a reduction of friction.
- A horizontal push does not change her weight (weight is the vertical gravitational force).
- A purely horizontal push does not change the vertical normal force from the ground (unless the push has a vertical component).
Why: by Newton’s third law the harder Kamala pushes the wall, the harder the wall pushes back on her. That larger horizontal reaction force is the net horizontal force that accelerates her backward (F = ma), so she rolls faster.
Why the others are wrong:
- Friction between the wheels and ground decreasing is not the reason; rolling motion is driven by the horizontal push from the wall, not a reduction of friction.
- A horizontal push does not change her weight (weight is the vertical gravitational force).
- A purely horizontal push does not change the vertical normal force from the ground (unless the push has a vertical component).
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