Problem 2 An ideal spring (k 200 N/m) is compressed by a 1.5 kg block. The sprin

Question

Problem 2 An ideal spring (k 200 N/m) is compressed by a 1.5 kg block. The spring is released. Find (a the speed of the block as it leaves the spring, and (b) the distance it will travel on the horizontal floor if H 0.2. Problem 3 A 5-kg ball is dropped vertically from a height of 10 m onto a floor. The ball rebound vertically to a height of 5 m. (a) What impulse acts on the ball during the contact? (b) If the ball is in contact with the floor for 0.008 s, what is the magnitude of average force on the ball from the floor?

Explanation / Answer

2. distane by which spring is compressed is not given that is reuiqred to solve.

suppose it is compressed by d then,

k d^2 /2 + 0 = 0 + m v^2 /2

200 d^2 = 1.5 v^2

v = sqrt(200/1.5) d

(B) f = - uk m g so a = - uk g

vf^2 - vi^2 = 2 a s

0^2 - (200 d^2 / 1.5) = 2 (-0.2 x 9.8)(s)

s = 5.83 d

3. v = sqrt(2 g h )

(A) speed just before strike,

vi = - sqrt(2 x 9.8 x 10) = -14 m/s

and vf = + sqrt(2 x 9.8 x 5) = 9.9 m/s

impulse = change in momentum

= 5 (9.9 - (-14))

= 119.5 kg m/s

(b) impulse = F t

119.5 = F(0.008)

F = 1.49 x 10^4 N

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