# physics

In loading a lorry a man lifts boxes each of weight 100N throughta height of 1.5 m. a)how much work does he do in lifting 1 box b)how much energy is transferred when 1 box is lifted c)if he lifts 4 boxes/minute@ what power is he working

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1. a. W = Fd = 100 * 1.5 = 150 Joules.

b. E = mgh = 100 * 1.5 = 150 Joules.

c. V = 4boxes/min * 1.5m/box * (1/60)min/s = 0.1m/s.

Po = FV = 100 * 0.1m/s = 10 Joules/s =
10 Watts.

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2. a.work done = 100*1.5 = 15o Joules
b.energy = 10*10*1.5 = 150 Joules
c.power = 150 / 60 = 2.5 W

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3. Work done =m*g*h
(m*g =weight)
Then,work=100*1.5
=150J

Work done = Energy consumed
=150J

Power=work done/time taken
=4*150/60
=10W

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5. Kobochan pushes a 28 kg filing cabinet 2.1 meter across the floor, doing 88.2 Joules of work. How much force is he applying to the cabinet?

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