Question

A horizontal force of 10 N is necessary to just hold a block stationary against a wall. The coefficient of friction between the block and the wall is 02. The weight of the block is
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Answer 1

CORRECT QUESTION :-

• A horizontal force of 10 N is necessary to just hold a block stationary against a wall. The coefficient of friction between the block and the wall is 0.2. The weight of the block is ?

ANSWER :-

• Weight of the block is 2N.

GIVEN :-

• Horizontal force of 10N is necessary to just hold the block stationary against the wall.
• Coefficient of friction between block and wall is 0.2.

TO FIND :-

• Weight of the block.

TO KNOW :-

★ Frictional Force = μ × Normal

• Here , 'μ' is coefficient of friction.

CONCEPT :-

• The block will tend to fall in downward direction , so friction will act in upward direction. Weight of the block is in downward direction. As the block is stationary , upward and downward forces acting on the body will be also equal.

SOLUTION :-

Firstly we will find the Frictional Force actiong on the block in the upward direction.

Using the formula ,

Frictional force = 0.2 × 10

Frictional force = 2N

So, as the ball is stationary , net forces acting on the body is also 0.

Upward Force = Weight (downward force)

Hence , weight of the block is 2N.

MORE TO KNOW :-

• Coefficient of friction(μ) is unitless.
• Whenever the object is stationary , net force acting on that object is 0.
• Normal force is the perpendicular force exerted by the body against the point of contact.