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A 1,220-N crate is being pushed across a level floor at a constant speed by a fo

ID: 1335159 • Letter: A

Question

A 1,220-N crate is being pushed across a level floor at a constant speed by a force F of 370 N at an angle of 20.0° below the horizontal.

A)What is the coefficient of kinetic friction between the crate and the floor? (Enter your answer to at least three decimal places.)

B) If the 370-N force is instead pulling the block at an angle of 20.0° above the horizontal, as shown in the figure b, what will be the acceleration of the crate? Assume that the coefficient of friction is the same as that found in part (a)

Explanation / Answer

(A) Force componet pushing the crate is = 370 cos 20

normal force=1220- 370 sin20

For constant speed , zero acceleration,

force of push=friction force

friction force=coeeficient of friction* normal force

constant speed friction force= force of push

coefficient of friction=370 cos20/(1220-370 sin20)

=0.318

(B)

Push below the horizonal is same as pull above the horizontal.

coeeficient of friction being the same , acceleration is zero.