# A box of books weighing 347 N is shoved across the floor by a force of 492 N exerted downward at an angle of 31◦below the hori-zontal.?

Update:

The acceleration of gravity is 9.81 m/s2.If μk between the box and the floor is 0.59,how long does it take to move the box 4.70 m,starting from rest?

### 1 Answer

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- NCSLv 76 months agoFavorite Answer
Method:

find the net horizontal force

find the net horizontal acceleration

find the time

normal force

Fn = mg + FsinΘ = 347N + 492N*sin31º = 600 N

friction force

f = µk*Fn = 0.59 * 600N = 354 N

net horizontal force

Fnet = FcosΘ - f = 492N*cos31º - 354N = 67.5 N

acceleration

a = Fnet / m = 67.5N / (347/9.81 kg) = 1.91 m/s²

from s = ½at²

we get

t = √(2s / a) = √(2 * 4.70m / 1.91m/s²) = 2.22 s

Hope this helps!

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