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A 0.297-kg block resting on a frictionless, horizontal surface is attached to a

ID: 1448715 • Letter: A

Question

A 0.297-kg block resting on a frictionless, horizontal surface is attached to a spring having force constant 83.8 N/m as in the figure below. A horizontal force

causes the spring to stretch at a distance of 5.69 cm from its equilibrium position.

(a) Find the value of F. (Enter the magnitude of the force only.)
N

(b) What is the total energy stored in the system when the spring is stretched?
J

(c) Find the magnitude of the acceleration of the block immediately after the applied force is removed.
m/s2

(d) Find the speed of the block when it first reaches the equilibrium position.
m/s

(e) If the surface is not frictionless but the block still reaches the equilibrium position, how would your answer to part (d) change?

The block would arrive at a greater speed.

The block would arrive at a lower speed.    

The block would arrive at the same speed.

Explanation / Answer

a) F=kx = 83.8*0.0569 = 4.77 N

b) ETotal = 1/2kA^2 = ½*83.8*0.0569^2 = 0.136 J

c) Fnet = ma

-kx = ma

a= (-kx)/m = (-83.8*0.0569)/0.297 = -16.05 m/s^2

d) By law of conservation of energy

KE= ETotal

1/2mv^2 = ETotal

½*0.297*v^2 = 0.136      => v= 0.97m/s

e)

The block would arrive at the same speed.

Reason: By the law of conservation of energy there is no loss in gravitational or in frictional forces.