# Physics-forces

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1. a force of 250N is used to push a heavy box down the street. If the force of friction between the box and the street is 195N and the box has a mass of 60kg, what is the accleration of the box?

2.a force of 40N is applied to a 6kg box of books. If the frictional force acting on the box is 16N, and the box was initially at rest, what is the velocity of the box 10s later? What is the box's displacement over the 10s period?

• Physics-forces -

F = m a
250 - 195 = 60 a
a = (250-195)/60
=======================
F = 40 - 16 = 24 N
a = F/m = 24/6 = 4 m/s^2
v = a t
v = 4*10 = 40 m/s
average speed over the ten seconds = 20m/s
displacement = 20 t = 200 m

• Physics-forces -

thanks!

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