Question

Denise is riding her bike and falls to the ground. During the collision, she hits both grass and cement.

Which best explains why Denise had fewer injuries to the area of her body that hit the grass?

The grass did not exert a reaction force.
The grass did not exert an action force.
The grass shortens the time of the collision.
The grass extends the time of the collision.

Answer 1

D. The grass extends the time of the collision

Step-by-step explanation:

The soft grass extends the time of the collision so the body has less of a dramatic impact on the ground.

Answer 2

According to Newton's second law, the rate of change of momentum is equal to the force acted on the body.

Hence, when the Denise hits the grass, the time duration of the collision increases due to which the rate of change of momentum decreases. Hence, the force acted on Denise's body will be smaller when it hits the grass as compared to the force acted on the Denise's body when it hits the cement as the time of collision with the cement will be smaller.

Δp = F × t

Hence, the option (D) is correct. The grass extends the time of collision.