IIT-JEE 2011 · Paper 1 · Physics Q41

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PhysicsInteger+4Question 41 of 69

A block is moving on an inclined plane making an angle 45° with the horizontal and the coefficient of friction is $\mu$ . The force required to just push it up the inclined plane is 3 times the force required to just prevent it from sliding down. If we define $N=10\mu$ , then $N$ is

Your answer

Answer and worked solution

Official answer: 5

Forces at 45°. Push up: $mg(\sin45°+\mu\cos45°)$ ; hold from sliding: $mg(\sin45°-\mu\cos45°)$ .

Condition. $1+\mu=3(1-\mu)$ gives $\mu=\frac12$ , so $N=5$ .

Answer: 5

Topics:Friction

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IIT-JEE 2011 · Paper 1, Physics question 41