A large crate of mass m is placed on the back of a truck but not tied down. As the truck accelerates forward with an acceleration a, the crate remains at rest relative to the truck. What force causes the crate to accelerate forward?

Anormal force
Bforce of gravity
Cforce of friction between the crate and the floor of the truck
Dthe "ma" force
Enone of these

"Force of friction between the crate and the floor of the truck" is the one force among the choices given in the question that causes the crate to accelerate forward. The correct option among all the options that are given in the question is the third option or option "c". I hope the answer helps you.

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facundo3141592 facundo3141592 · Answer 2 · 2020-03-09T21:26:45-04:00

Answer: Option C

Explanation: Let's analyze each possible force:

A)normal force, it pushes in the direction in which the box has contact with some surface, in this case, is in the bottom of the truck, so this force pushes upwards.

B) Force of gravity always pushes downwards, so it can not accelerate the box in the same direction in which the truck is moving.

c) The force of friction points in the opposite direction in which the box would move, if the truck moves to the right, the box will move to the left, so the friction pushes also to the right, which is the same direction in which the truck is moving.

D) there is nothing called the "ma" force.

Now, the correct option would be C; the force of friction (the statical one, because we know that the box does not move)