Answer:
40 N
Explanation:
Newton's second law of motion states that the net force acting on the crate is equal to the product between its mass and its acceleration:
where
m is the mass
a is the acceleration
In this problem, we have:
- The net force can be written as
where
F = 40 N is the horizontal forward push
is the force of friction
Also, we know that the crate moves at constant velocity, so its acceleration is zero:
By combining all the equations together, we find:
So, the force of friction is 40 N.
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