Question

3. A 5kg block is connected to a 3kg block by means of a string that passes over a pulley. Find the (a) unbalanced force, (b) acceleration of the blocks, and (c) tension in the string. Assume that the pulley and the surfaces are frictionless.

Answer 1

(a) The unbalanced force is

$$F_u=g(M-m)=19.6\text{ N}.$$

(b) acceleration of the blocks:

$$a=F/(M+m)=g\dfrac{M-m}{M+m}=2.45\text{ m/s}^2.$$

(c) tension in the string:

$$T=m(g+a)=M(g-a)= 36.75\text{ N}.$$