Question

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.

Answer 1

Answer: Second option "The force of the wall pushing on her increases."

Explanation: This is because of Newton's third law: For every action (force) in nature, there is an equal and opposite reaction.

So when Kamala pushes against the wall, the wall is also pushing against Kamala, and this is what impulses her backward. So if she uses more force, then the wall sill apply more force on her, and then she will roll faster.

The right answer is then the second option: "The force of the wall pushing on her increases."

Answer 2

Because the force of the wall pushing on her increases.

According to Newton's third law of motion, to every action there is an equal and opposite reaction. When the Kamala pushes the wall, the wall also pushes her. Pushing harder against the wall causes the force of the wall pushing her also increase. Thus, making her roll faster.