Two blocks rest on a horizontal, frictionless table. The lower block (call it A)

ID: 1535199 • Letter: T

Question

Two blocks rest on a horizontal, frictionless table. The lower block (call it A) has

a mass of 35 kg while the upper block (call it B) has a mass of 15 kg. A force of

100 N is applied to the lower block and the two blocks accelerate together.

(a) What is the acceleration of this collection of blocks?

(b) Determine all the forces (magnitude and direction) acting on block B.

(d) What is the minimum coefficient of static friction that is required to keep the

blocks together in the present case

(a)

a = F / (mA + mB)

a = 100 / (35 + 15)

a = 50 m/s^2

(d)

let, minimum coefficient of static friction = u

F = Fr

F = u*N

where N = normal force on upper block = mB*g

100 = u*15*9.8

u = 0.68

(b)

On block B,

friction force is acting on its base (-x direction)

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