Home
Class 9
PHYSICS
A machine is used to lift a 100-kg stone...

A machine is used to lift a 100-kg stone through a vertical height 20 m in 80 s. Find the useful power of the machine. If the efficiency of the machine is 75%, find the electric power consumed by the machine. [Take g = `10 ms^(-2)`]

Text Solution

Verified by Experts

Useful power `=("useful work")/("time") =(mgh)/t`
`=(00 xx 10 xx 20)/80 = 250 W` (power output)
`E =("Power output")/("Power input")`
`therefore 75/100 = 250/("power input")`
`therefore` Power input `=250 xx 100/75 = 333 W`
Promotional Banner

Topper's Solved these Questions

  • STATICS

    CENGAGE PHYSICS|Exercise MANDATORY EXERCISE (EXERCISE SET I) (SHORT ANSWER QUESTIONS) |8 Videos

  • STATICS

    CENGAGE PHYSICS|Exercise MANDATORY EXERCISE (NUMERICALS) |5 Videos

  • SOUND

    CENGAGE PHYSICS|Exercise OLYMPIAD AND NTSE LEVEL EXERCISE|10 Videos

  • UNITS AND MEASUREMENT

    CENGAGE PHYSICS|Exercise OLYMPIAD AND NTSE LEVEL EXERCISES |8 Videos

Similar Questions

Explore conceptually related problems

An engine pumps 800 kg of water through height of 10 m in 80 s. Find the power of the engine if its efficiency is 75%

An engine pumps 400 kg of water through height of 10 m in 40 s. Find the power of the engine if its efficiency is 80% (Take ,g =10 ms^(-2) ).

An engine pumps up 100 kg water through a height of 10 m in 5 s . If effcienecy of the engine is 60% . What is the power of the engine? Take g = 10 ms^(2) .

A crane lifts a mass of 100 kg to a height of 10 m in 20 s. The power of the crane is (Take g = 10 m s^(-2) )

A crane can lift up 10,000 kg of coal in 1 hour form a mine of 180 m depth. If the efficiency of the crane is 80 % , its input power must be (g = 10 ms^(-2)) .

A machine can take out 1000 kg of mud hour from a dept of 100 m . If efficieny of the machine is 0.9 , calculate its power.

A crane lifts a mass of 100 kg to a height of 10m in 20s . The power of the crane is (Take g = 10 ms^(-2))