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

Grass gives way more than cement, increasing the time over which Denise slows down during the collision. For the same change in momentum, a longer collision time means a smaller average force, so the grass extends the time of the collision. The grass still exerts both an action and a reaction force.

AI-written and checked against the verified answer.