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
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.
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
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?
a) Well, lifting boxes can be quite uplifting! The man is doing work equal to the force multiplied by the distance. So lifting one box weighing 100N through a height of 1.5m would result in 150 Joules of work. That's a lot of heavy lifting!
b) When the man lifts one box, he transfers energy equal to the work done. So, in this case, lifting one box transfers 150 Joules of energy. Now the box has some extra potential energy to throw around!
c) If the man lifts 4 boxes per minute, we need to consider how much work is done in total over that time period. Since he does 150 Joules of work for each box, lifting 4 boxes would result in a total work of 600 Joules. Now, power is work done per unit of time, so if he lifts boxes at this rate, he is working at a power of 600 Joules per minute. That's some serious box-lifting power!
To answer these questions, we need to use the formulas for work, energy, and power. Let's break down each question and calculate the values step by step.
a) How much work does he do in lifting 1 box?
The formula for work is given by:
Work = Force × Distance
In this case, the force is the weight of the box (100N) and the distance is the height the box is lifted (1.5m). Plugging in these values into the formula, we get:
Work = 100N × 1.5m
= 150 joules (J)
So, the man does 150 joules of work in lifting 1 box.
b) How much energy is transferred when 1 box is lifted?
The amount of energy transferred in this case is the same as the work done on the box. In our previous calculation, we found that the work done was 150 joules (J), so the energy transferred is also 150 joules (J).
c) If he lifts 4 boxes/minute, at what power is he working?
Power is the rate at which work is done or energy is transferred. It is calculated using the formula:
Power = Work / Time
Here, we know the work done per box is 150 joules (J), and the time taken to lift 4 boxes is 1 minute. Plugging in these values into the formula, we get:
Power = 150J / 1 minute
= 150J / 60 seconds (since there are 60 seconds in a minute)
= 2.5 joules per second (J/s), or 2.5 watts (W)
So, the man is working at a power of 2.5 watts (W) when lifting 4 boxes per minute.
To summarize:
a) The man does 150 joules (J) of work in lifting 1 box.
b) The energy transferred when 1 box is lifted is also 150 joules (J).
c) The man is working at a power of 2.5 watts (W) when lifting 4 boxes per minute.
helpful
a.work done = 100*1.5 = 15o Joules
b.energy = 10*10*1.5 = 150 Joules
c.power = 150 / 60 = 2.5 W