हिंदी

Choose one or more correct alternatives. Power is a measure of the ______. The rapidity with which work is done. Amount of energy required to perform the work. The slowness with which

Advertisements
Advertisements

प्रश्न

Choose one or more correct alternatives.

Power is a measure of the ______.

  1. The rapidity with which work is done.
  2. Amount of energy required to perform the work.
  3. The slowness with which work is performed.
  4. Length of time.
रिक्त स्थान भरें
Advertisements

उत्तर

Power is a measure of the rapidity with which work is done and the slowness with which work is performed.

shaalaa.com
  क्या इस प्रश्न या उत्तर में कोई त्रुटि है?
अध्याय 2: Work and Energy - Exercises [पृष्ठ २८]

APPEARS IN

बालभारती Science and Technology [English] Standard 9 Maharashtra State
अध्याय 2 Work and Energy
Exercises | Q 2. d. | पृष्ठ २८

संबंधित प्रश्न

The blades of a windmill sweep out a circle of area A.

  1. 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?
  2. What is the kinetic energy of the air?
  3. 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?

A family uses 8 kW of power.

  1. Direct solar energy is incident on the horizontal surface at an average rate of 200 W per square meter. If 20% of this energy can be converted to useful electrical energy, how large an area is needed to supply 8 kW?
  2. Compare this area to that of the roof of a typical house.

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 

1 H.P. is equal to


An electric heater of power 3 kW is used for 10 h. How much energy does it consume? Express your answer in

  1. kWh,
  2. joule.

State and define the S.I. unit of power.

Arrive at an expression for power and velocity. Give some examples for the same.


A ball with a velocity of 5 ms−1 impinges at an angle of 60˚ with the vertical on a smooth horizontal plane. If the coefficient of restitution is 0.5, find the velocity and direction after the impact.


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 develops 20 kW power. How much time will it take to lift a mass of 200 kg to a height of 50 m? (g = 10 m/s2)


Water falls from a height of 60 m at the rate of 15 kg/s to operate a turbine. The losses due to frictional force are 10% of the input energy. How much power is generated by the turbine? (g = 10m/s2)


Water falls from a height of 60 m at the rate of 15 kg/s to operate a turbine. The losses due to frictional force are 10% of the input energy. How much power is generated by the turbine? (g = 10 m/s2)  


A man is throwing bricks of mass 2 kg onto a floor from a height of 2 m. Bricks reach the floor at a speed `2sqrt(10)` m/s. Man throws 10 bricks in a minute. If the power of man is W watt then `3/10` W is equal to ______ W.


Name the quantity which is measured in kWh.


Name the quantity which is measured in Wh.


At any instant of time t, the displacement of any particle is given by 2t – 1 (SI unit) under the influence of force of 5N. The value of instantaneous power is (in SI unit):


Share
Notifications

Englishहिंदीमराठी


      Forgot password?
Use app×