Question

As you are walking, you foot gets caught on an uneven piece of sidewalk and you trip and fall. Which of the following explains what is happening using Newton's Laws?





(1 point)
Responses

The sidewalk pushed you, causing a rapid force that made you fall
The sidewalk pushed you, causing a rapid force that made you fall

The sidewalk provided a force to stop your foot, but the top of your body was still moving, which is what causes you to tip over
The sidewalk provided a force to stop your foot, but the top of your body was still moving, which is what causes you to tip over

Your foot hit the sidewalk and provided a force on it, so the sidewalk will provide another force back on your foot, equal in magnitude but opposite in direct
Your foot hit the sidewalk and provided a force on it, so the sidewalk will provide another force back on your foot, equal in magnitude but opposite in direct

Your foot pushes the sidewalk with such force that it causes the next piece of sidewalk to be uprooted, which makes your next step miss your footing

Answer 1

The sidewalk provided a force to stop your foot, but the top of your body was still moving, which is what causes you to tip over.

Explanation: by Newton’s first law your upper body (and its center of mass) tends to keep moving forward when your foot is suddenly stopped. That creates a forward rotation (torque) about the contact point and you topple. (Newton’s third law also applies: the foot pushes on the sidewalk and the sidewalk pushes back with an equal and opposite force that stops the foot.)