# Physics (work and springs)

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A 4kg box is compressed 50cm on a spring (k=800 N/m) and then slides across a horizontal floor. If (u=0.4) between the box and the floor...

A) how much work is done?
B) assuming the frictional force is constant, how far will the box slide before it comes to a stop?

• Physics (work and springs) -

A)
The elastic potential energy stored in the spring would convert into KE of the box. This KE would be dissipated while working against the frictional force.
So work done = (1/2)Kx^2
= 800*0.5^2/2
= 100 Joules
B)
Frictional force F= mu*mg
F = 0.4*4*10 = 16 N

Work done = F*d
d = 100/16 = 6.25 m

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