Advertisements
Advertisements
प्रश्न
A boy weighing 40 kg carries a box weighing 20 kg to the top of a building 15 m high in 25 seconds. Calculate the power. (g = 10 m/s2)
उत्तर
Mass of the boy, (m1) = 40 kg
Mass of the box, (m2) = 20 kg
Height, (h) = 15 m
Acceleration due to gravity, (g) = 10 m/s2
Time taken, (t) = 25 s
Total mass of the system,
M = m1 + m2
=> M = 40 + 20 = 60 kg
So, work done by the boy is,
W = mgh
=> W = (60)(10)(15)
=> W = 9000 J
Now, we can calculate the power of the boy as,
Power = `"Work done"/"Time"`
So ,
Power = `9000/25` W
= 360 W
So, the power is 360 W.
APPEARS IN
संबंधित प्रश्न
A lamp consumes 1000 J of electrical energy in 10 s. What is its power?
Define average power.
A battery lights a bulb. Describe the energy changes involved in the process.
A load of 100 kg is pulled up by 5 m. Calculate the work done. (g = 9.8 m/s2)
A man weighing 500 N carried a load of 100 N up a flight of stairs 4 m high in 5 seconds. What is the power?
A car of weight 20000 N climbs up a hill at a steady speed of 8 m/s, gaining a height of 120 m is 100 s. Calculate : power of engine of car.
In an experiment to measure his power, a student records the time taken by him in running up a flight of steps on a staircase. Use the following data to calculate the power of the student :
Number of steps = 28
Height of each step = 20 cm
Time taken = 5.4 s
Mass of student = 55 kg
Acceleration = 9.8 m s−2
due to gravity
In loading a truck, a man lifts boxes of 100 N each through a height of 1.5 m.
How much work does he do in lifting one box?
In loading a truck, a man lifts boxes of 100 N each through a height of 1.5 m.
If the man lifts 4 boxes per minute, at what power is he working?
(g = 10 m s−2)
How is the power related to the speed at which a body can be lifted? How many kilograms will a man working at the power of 100 W, be able to lift at a constant speed of 1 m s–1 vertically? (g = 10 m s–2)
