Question

In the figure shown coefficient of friction between 8 kg block and surface is zero and coefficient of friction (both static and kinetic) between the blocks is 0.4. A force of 20 N is applied on 8 kg block as shown. The acceleration of 4 kg mass is
(g = 10 m/s²
(1) 4 m/s²
(2) 0.5 m/s² (3)5/3m/s² (4)3/5m/s²​

Answer 1

Answer:

The answer is 5/3 m/s2.

Explanation:

There is no any direct force on the 4 kg block ony friction is responsible for the motion of 4 kg block.

F = μmg

 = 0.4 x 4 x 10 = 16 N

Maximum possible acceleration = F/m = 16 / 4  

                                                            = 4 m/s2

Lets both block move together.

Fnet = ma

20 = ( 4+ 8)a

20 = 12a

a = 20 /12

a = 5/3 m/s2

Thus they will move together with 5/3 m/s2 acceleration.