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# A block of mass 2.5 kg is attached to a horizontal spring that has a force constant of 1.40 103 N/m?

and is free to slide on a frictionless surface as shown. The spring is compressed to

xi = −5.5 cm by pushing on the block, and then the block is released.

Find the work done by initially compressing the spring.

J

Find the kinetic energy of the block when it reaches x = 0.

J

Find the speed of the block at x = 0.

m/s

### 1 Answer

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- NCSLv 72 months agoFavorite Answer
Given:

m = 2.5 kg

k = 1.40e3 N/m

xi = -5.5 cm = -0.055 m

(a) work W = ½k(xi)² = ½ * 1.40e3N/m * (-0.055m)² = 2.12 J

(b) At x = 0, KE = W = 2.12 J

(c) KE = 2.12 J = ½ * 2.5kg * v² → v = 1.30 m/s

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