Figure shows two block system, 4 kg block rests on a smooth horizontal surface, upper surface of 4 kg is rough. A block of mass 2 kg is placed on its upper surface. The acceleration of upper block with respect to earth when 4 kg mass is pulled by a force of 30 N, is

Question

Figure shows two block system, 4 kg block rests on a smooth horizontal surface, upper surface of 4 kg is rough. A block of mass 2 kg is placed on its upper surface. The acceleration of upper block with respect to earth when 4 kg mass is pulled by a force of 30 N, is (A) 6 m / s 2 (B) 5 m / s 2 (C) 8 m / s 2 (D) 2 m / s 2

Tardigrade Admin · Accepted Answer

It both move together a=(30/(4+2))=5 m / s 2 2 kg will move due to frictional force F=m a ⇒ f=2(5)=10 N and limiting friction fL=(0.8)(2 g)=16 N ⇒ Friction is sufficient to move both block together hence a=5 m / s 2

Q. Figure shows two block system, $4 k g$ block rests on a smooth horizontal surface, upper surface of $4 k g$ is rough. A block of mass $2 k g$ is placed on its upper surface. The acceleration of upper block with respect to earth when $4 k g$ mass is pulled by a force of $30 N$ , is

$6 m / s^{2}$

$5 m / s^{2}$

$8 m / s^{2}$

$2 m / s^{2}$

It both move together
$a = \frac{30}{( 4 + 2 )} = 5 m / s^{2}$
$2 k g$ will move due to frictional force
$F = ma \Rightarrow f = 2 (5) = 10 N$
and limiting friction $f_{L} = (0.8) (2 g) = 16 N$
$\Rightarrow$ Friction is sufficient to move both block together hence $a = 5 m / s^{2}$

Q. Figure shows two block system, 4kg block rests on a smooth horizontal surface, upper surface of 4kg is rough. A block of mass 2kg is placed on its upper surface. The acceleration of upper block with respect to earth when 4kg mass is pulled by a force of 30N, is

6m/s2

5m/s2

8m/s2

2m/s2