Work, Energy and Power- Objective Questions


11. Initially, mass m is held such that spring is in a relaxed condition. If mass m is suddenly released, maximum elongation in the spring will be?

  • mg / k
  • 2mg/k
  • mg/2k
  • mg/4k
Click for Answer/Explanation

2mg/k

12. The power of the water pump is 4 kW. If g = 10 m/s², the amount of water it can raise in 1 minute to a height of 20 m is (1 liter = 1Kg)

  • 100 liter
  • 1000 liter
  • 1200 liter
  • 2000 liter
Click for Answer/Explanation

1200 litre

13. A body is projected from ground obliquely. During downward motion, the power delivered by gravity to it

  • Increases
  • Decreases
  • Remains constant
  • First decreases and then becomes constant
Click for Answer/Explanation

Increases

14. The blades of a windmill sweep out a circle of area A. If the wind flows with velocity v perpendicular to blades of the windmill and its density is? then the mechanical power received by the windmill is?

  • ρAv³/2
  • ρAv²/2
  • ρAv²
  • 2 ρAv²
Click for Answer/Explanation

ρAv³/2

15. The power of a pump, which can pump 500 kg of water to height 100 m in 10 seconds is

  • 75 Kw
  • 25 kW
  • 50 kW
  • 500 kW
Click for Answer/Explanation

50 kW

Read More ⇒ States of Matter Objective Questions

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