While pushing a 100kg box of stage props across a floor you push the box at a 20 degree angle below horizontal with a force of 500N.The coefficient of friction between the box and the floor is 0.40N/N

Question

A) What is its horizontal acceleration across the floor?

B) How long will it take to push the box 20 meters across the stage if you manage to maintain that force all the way?

Answer 1

Hi Zoey C.,

1) Decompose the pushing force into a vertical and a horizontal component, using sine and cosine of the angle respectively.

2) Figure the total vertical force resultant from the pushed box onto the floor. That's from its own mass (use F=mg ) plus the vertical component of the push force.

3) From the coefficient of friction given, figure the frictional force by the floor onto the box. That force opposes the horizontal component of the push force; figure the net horizontal force.

4) From the net horizontal force and the box mass, figure its acceleration (use F=ma).

5) You should already know the equation relating d, a, and t.

-- Cheers, -- Mr. d.

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