A fireman wants to slide down a rope. The breaking load of the rope is 3/4 of the weight of the man. With what acceleration should the fireman slide down? (Acceleration due to gravity is 'g')
Correct answer: B. g/4
- A. g
- B. g/4
- C. 3g/4
- D. 0
Explanation
Newton's second law states that the force required to accelerate a body is equal to the product of its mass and acceleration. The acceleration will be smaller for a large mass. As a result, more force is required to accelerate the body. The force is imparted through the rope as the firefighter slides down it. Tension is the force exerted on the rope. The minimum tension at the rope when the fireman slide down us given as, mg - ¾ mg This force equating with the minimum tension at the rope, we get: ma = mg - ¾ mg a = g - ¾ g a = g (1 - ¾) a = g/4 The fireman should slide down with a minimum acceleration of ¼ of the acceleration due to gravity.
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