Advertisements
Advertisements
Question
A lamp consumes 1000 J of electrical energy in 10 s. What is its power?
Advertisements
Solution
Power = `"Energy consumed (or work done)"/"Time taken"`
W = 1000 J, t = 10 s
i.e., P = `W/t`
= `(1000 J)/(10 s)`
= 100 J/s
i.e., P = 100 W
APPEARS IN
RELATED QUESTIONS
A battery lights a bulb. Describe the energy changes involved in the process.
What is the work done by the force of gravity on a satellite moving round the earth? Justify your answer.
Find the energy in joules consumed in 10 hours by four devices of power 500 W each.
Name the physical quantity whose unit is watt.
Fill in the blanks with suitable words :
One watt is a rate of working of one ___________ per ___________.
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?
The power output of an engine is 3kW. How much work does the engine do in 20 s?
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 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)
An electric motor raises a load of 0.2 kg, at a constant speed, through a vertical distance of 3.0 m in 2 s. If the acceleration of free fall is 10 m/s2, the power in W developed by the motor in raising the load is :
