Part A: A 0.26-kg rock is thrown vertically upward from the top of a cliff that

Question

Part A: A 0.26-kg rock is thrown vertically upward from the top of a cliff that is 32 m high. When it hits the ground at the base of the cliff, the rock has a speed of 29 m/s .

Assuming that air resistance can be ignored, find the initial speed of the rock.

Find the greatest height of the rock as measured from the base of the cliff.

Part B Question 1 A 1.90 kg block slides on a rough horizontal surface. The block hits a spring with a speed of 2.00 m/s and compresses it a distance of 11.0 cm before coming to rest. If the coefficient of kinetic friction between the block and the surface is 0.460, what is the force constant of the spring?

Explanation / Answer

a) 1) form the conservation of eneergy

mgh+1/2mu^2 = 1/2mv^2

1/2mu^2 = 1/2mv^2-mgh

u^2 = v^2-2gh

u = sqrt(29^2-2*9.8*32) = 14.62 m/s

2) mgh = 1/2mv^2

h = v^2/2g = 29^2/2*9.8 = 42.91 m

b) w tot = 1/2mv^2

wtot = 1/2kx^2-mue*mg = 1/2mv^2

1/2kx^2 = 1.9(2^2/2+0.46*9.8) = 12.36

k = 2*12.36/0.11^2 = 2043.8 N/m

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