Home
Class 12
PHYSICS
A petrol engine consumes 20 kg of petrol...

A petrol engine consumes 20 kg of petrol per hour. The calorific value of the fuel is `1 xx 10^(7)` cal/kg. The power of the engine is 84 kilowatt. Calculate the efficiency of the engine.

A

`36 %`

B

`46 %`

C

`28 %`

D

`58 %`

Text Solution

Verified by Experts

The correct Answer is:
a
Petrol consumed by the engine,
`m_(f) = 20/(60 xx 60) kg//s`
Heat released due to the combustion of fuel,
`Q = m_(f) xx ` calorific value of the fuel ` = 20/(60 xx 60) xx 1 xx 10^(7)`
` = 10^(6)/18 " cal/s" = 10^(6)/18 xx 4.2 " joule /s " = 700/3 ` kW
Power produced by the engine , `W = 84 kW`
` :. ` Effeciency of the engine
` = W/Q xx 100 = 84/(700//3) xx 100 = 36% `
Promotional Banner

Topper's Solved these Questions

  • THERMODYNAMICS

    MTG-WBJEE|Exercise WB JEE WORKOUT ( CATEGORY 3 : One or Mare than One Option Correct Type (2 Mark )|10 Videos

  • THERMODYNAMICS

    MTG-WBJEE|Exercise WB JEE Previous Years Questions|12 Videos

  • THERMODYNAMICS

    MTG-WBJEE|Exercise WB JEE Previous Years Questions|12 Videos

  • SOLID STATE ELECTRONS

    MTG-WBJEE|Exercise WB JEE Previous Years Questions (CATEGORY 1 : Single Option Correct Type)|15 Videos

  • WAVE OPTICS

    MTG-WBJEE|Exercise WB JEE PREVIOUS YEARS QUESTION (MCQ.s)|9 Videos

Similar Questions

Explore conceptually related problems

A petrol engine consume 25 kg of petrol per hour. The calorific value of petro lis 11.4xx 10^(6) cal kg^(-1) . The power of the engine is 99.75 kW. Calculate the efficiency of the engine.

In a petrol engine, the rate of production of heat due to combustion of the fuel is 5xx10^(6) cal h^(-1) . The efficiency of the engine is 30%. Calculate the H.P. of the engine. Given, J=4.2 J cal^(-1) and 1 h.p. =746 W.

In a petrol engine,the rate of production of heat due to the combustion of petrol is 7.46xx10^(5) cal h^(-1) . The efficiency of the engine is 30%. Calculate the horse power of the engine, if J is 4.2xx10^(7) erg cal^(-1)

An enegine is used to lift a 2700 kg truck to a height of 3.0 m at constant speed . In the lifting process , the engine received 3.3 xx 10^5 J of heat from the fuel burned in its interior . What is the efficiency of the engine ?

A pump can throw up 10 quntals of coal per hour from a coal mine 120m deep. Calculate the power of the engine in watt assuming that efficiency is 80% .