Block Against Vertical Wall – Rankers Physics
Topic: Laws of Motion
Subtopic: Friction

Block Against Vertical Wall


Assertion (A): A block of weight \(10 \text{ N}\) is pushed against a vertical wall by a horizontal force of \(15 \text{ N}\). The coefficient of friction between the wall and the block is \(0.6\). Then the magnitude of maximum frictional force is \(9 \text{ N}\).
Reason (R): For given system block will remain stationary.
 
(1) Both (A) & (R) are true and the (R) is the correct explanation of the (A)
(2) Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
(3) (A) is true but (R) is false
(4) Both (A) and (R) are false

Solution:

Normal force \(N = 15 \text{ N}\). Maximum static friction \(f_{\text{max}} = \mu_{\text{s}} N = 0.6 \times 15 = 9 \text{ N}\). So (A) is true. Weight of block is \(W = 10 \text{ N}\). Since \(W > f_{\text{max}}\), the block will slide down. So (R) is false.

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