text: # An object of mass 20 kg is lifted to a height of 5 m in 20 sec. The power required will be: (g=10m/s2)
  
  1. 50 watt
  2. 5 watt
  3. 500 watt
  4. 100 watt
  
  Option 1 : 50 watt
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  ## Detailed Solution
  
  CONCEPT:
  
  Power:
  
  • The rate of doing work is called power.
  • SI unit of power is the watt.
  
  $$⇒ P=\frac{W}{t}$$
  
  .Where P = power, W = work done and t = time
  
  CALCULATION:
  
  Given m = 20 kg, h = 5 m, t = 20 sec and g = 10 m/sec2
  
  • We know that the work done in lifting a body of mass m to height h is given as,
  
  ⇒  W = mgh    -----(1)
  
  By equation 1,
  
  ⇒  W = 20 × 10 × 5 = 1000 J
  
  • So power required,
  
  $$⇒ P=\frac{W}{t}$$
  
  $$⇒ P=\frac{1000}{20}$$
  
  $$⇒ P=50\,watt$$
  
  • Hence, option 1 is correct.
  
  Last updated on May 15, 2024
  
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