A block of mass is at rest under the action of force against a wall as shown in figure. Which of the following statement is incorrect? [2005]

Question

A block of mass $m$ is at rest under the action of force $F$ against a wall as shown in figure. Which of the following statement is incorrect? [2005]

Smart Achievers · Accepted Answer

(4)

The block is in equilibrium.

For translational equilibrium

$\sum F_{x} = 0 \Rightarrow F = N$

$\sum F_{y} = 0 \Rightarrow f = m g$

For rotational equilibrium

$\sum τ_{C} = 0$

Torque created by frictional force $(f)$ about $C = f \times a$ in clockwise direction.

There is another torque which should counter this torque.

The normal reaction N on the block will create a torque $N \times b$ in the anticlockwise direction.

Such that $f \times a = N \times b$

Hence N will produce torque.

Solution

Q.
A block of mass $m$ is at rest under the action of force $F$ against a wall as shown in figure. Which of the following statement is incorrect [2005]

1 $f = m g [f friction force]$

2 $F = N [N normal force]$

3 F will not produce torque

4 N will not produce torque

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