Firefighters traditionally use a pole to slide from their upstairs quarters to t

Question

Firefighters traditionally use a pole to slide from their upstairs quarters to their fire-trucks below. Responding to an alarm, a 220 lb fireman grabs the pole and slides down 15 m to the floor below. The net downward force, once he grabs the pole and begins to fall, is zero less than 220 lb 220 lb more than 220 lb acceleration friction Normal force gravity more than one of the above If the fireman had worn gloves he would slide down the pole more slowly. This is because of increased the coefficient of friction decreased the coefficient of friction increased normal force decreased normal force none of the above During his drop, after he's already slid 5 m down, the firefighter increases his grip on the pole, with the result that net force on him is now zero. He would continue to fall as before. He would continues to fall with lower acceleration (but not zero) He would continue to fall but with constant velocity He would stop at 5 m.

Explanation / Answer

1

(B)

down ward force varies with height, as fire frighter falls down down force decreases so down ward force after falling 15 m is less than the 220 lb( initial force)

(2)

friction force oppose the downward force , so it is always to opposite direction of down force.

so the direction of force is upward

(3)

the rough surface between the gloves and pole wall provide coefficient of frction, in this case ordinary hands thee firman falls with greater speed but after wearing gloves, the fall down becomes slow due to the increased coefficient of frction.

(4)

since net force is zero means the fire man continue ot fall with constant velocity , from Newton second law of motion, F = ma

0 = ma

a = constant = constatn velocity

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