Advertisements
Advertisements
प्रश्न
It takes 20 s for a girl A to climb up the stairs while girl B takes 15 s for the same job. Compare the power spent by then.
Advertisements
उत्तर
Power = `"Work done"/"Time taken "` = `"Energy" /"Time"`
= `"Power of A "/ "Power of B"` = `(" Energy "/ t_1 )/("Energy "/ t_2)`
= `1/t_1` ' `t_2/1` =`15/20`
= `3/4` = 3 : 4
APPEARS IN
संबंधित प्रश्न
The blades of a windmill sweep out a circle of area A.
- If the wind flows at a velocity v perpendicular to the circle, what is the mass of the air passing through it in time t?
- What is the kinetic energy of the air?
- Assume that the windmill converts 25% of the wind’s energy into electrical energy, and that A = 30 m2, v = 36 km/h and the density of air is 1.2 kg m–3. What is the electrical power produced?
Power P= ............ /time taken.
Match the following
| column A | Column B |
| A stone at a height | power |
| A Moving ball | joule |
| Energy | work done in 1 s |
| Power | potential energy |
| Watt | kinetic energy |
A pump raises water by spending 4×105J of energy in 10s. Find the power of the pump.
If a 1200 W electric iron is used daily for 30 minutes, how much total electricity is consumed in the month of April?
Arrive at an expression for power and velocity. Give some examples for the same.
A quarter horse power motor runs at a speed of 600 r.p.m. Assuming 40% efficiency, the work done by the motor in one rotation will be
An engine pumps up 200 kg of water through a height of 20 m in 10 seconds. If the efficiency of the engine is 80%. Calculate the power of the engine.
Name the quantity which is measured in kWh.
Name the quantity which is measured in eV.
