Block A of mass 1 kg is placed on the rough surface of block B of mass 3 kg. Block B is placed on smooth horizontal surface. Blocks are given the velocities as shown. The net work done by the frictional force is .[in (-) ve J]

Question

Block A of mass 1 kg is placed on the rough surface of block B of mass 3 kg. Block B is placed on smooth horizontal surface. Blocks are given the velocities as shown. The net work done by the frictional force is .[in (-) ve J] (A)  (B)  (C)  (D)

Tardigrade Admin · Accepted Answer

(1+3) v=(1)(8)+(3)(4)=20 v=5 m / sec For block A, Wf=(1/2)(1)(52-82)=-(39/2) J For block B, Wf=(1/2)(3)(52-42)=+(27/2) J Net work done by friction =-6 J

Q. Block $A$ of mass $1 k g$ is placed on the rough surface of block $B$ of mass $3 k g$ . Block $B$ is placed on smooth horizontal surface. Blocks are given the velocities as shown. The net work done by the frictional force is ______.[in (-) ve $J$ ]

$(1 + 3) v = (1) (8) + (3) (4) = 20 v = 5 m / sec$
For block $A, W_{f} = \frac{1}{2} (1) (5^{2} - 8^{2}) = - \frac{39}{2} J$
For block $B, W_{f} = \frac{1}{2} (3) (5^{2} - 4^{2}) = + \frac{27}{2} J$
Net work done by friction $= - 6 J$

Q. Block A of mass 1kg is placed on the rough surface of block B of mass 3kg. Block B is placed on smooth horizontal surface. Blocks are given the velocities as shown. The net work done by the frictional force is ______.[in (-) ve J]

(1+3)v=(1)(8)+(3)(4)=20v=5m/sec For block A,Wf​=21​(1)(52−82)=−239​J For block B,Wf​=21​(3)(52−42)=+227​J Net work done by friction =−6J

Q. Block $A$ of mass $1 k g$ is placed on the rough surface of block $B$ of mass $3 k g$ . Block $B$ is placed on smooth horizontal surface. Blocks are given the velocities as shown. The net work done by the frictional force is ______.[in (-) ve $J$ ]

$(1 + 3) v = (1) (8) + (3) (4) = 20 v = 5 m / sec$
For block $A, W_{f} = \frac{1}{2} (1) (5^{2} - 8^{2}) = - \frac{39}{2} J$
For block $B, W_{f} = \frac{1}{2} (3) (5^{2} - 4^{2}) = + \frac{27}{2} J$
Net work done by friction $= - 6 J$