Question

Two boxes A and B are connected by ropes A and B as shown in figure. A person is pulling rope A with a horizontal force along a horizontal and rough surface. Choose the correct free body diagram (FBD) of block A.

(If $F_f$= frictional force, $F_g$ = Gravitational force,$F_n$ = Normal force, $T_a$= Tension force applied by rope A, $T_b$= Tension force applied by rope B)

• A.
• B.
• C.
• D.

Answer 1

The correct option is D

Forces on the Box A are as follows.
1. Gravitational force ($F_g$) by the earth will act in downward direction.

2. Normal force ($F_n$) by the surface will act in vertically upward direction.

3. Since the man is pulling the rope in right direction the frictional force ($F_f$) will try to oppose the relative motion and will act towards left.

4. Since, tension is always pulling force, so it pulls from both ends. The tension force in rope A ($T_a$) will try to pull block A towards right.

5. Similarily, The tension force in rope B($T_b$) will try to pull block A towards left.