HARD
9th CBSE
IMPORTANT
Earn 100

A 500 W electric bulb lighted for 2 hours everyday and an electric motor of 0.5 horse power is used for 2 hours everyday. Calculate the cost of using the bulb and the motor for 30 days, if the cost of electrical energy is three rupees per unit.

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Important Questions on Work and Energy

MEDIUM
9th CBSE
IMPORTANT
Secondary Physics>Chapter 5 - Work and Energy>EXERCISES>Q 7
What is meant by power? Define the terms watt and kilowatt. Also state the bigger units of power.
MEDIUM
9th CBSE
IMPORTANT
Secondary Physics>Chapter 5 - Work and Energy>EXERCISES>Q 8
Derive the relationship between momentum and kinetic energy of a body.
MEDIUM
9th CBSE
IMPORTANT
Secondary Physics>Chapter 5 - Work and Energy>EXERCISES>Q 9

Differentiate between work, power and energy.

MEDIUM
9th CBSE
IMPORTANT
Secondary Physics>Chapter 5 - Work and Energy>EXERCISES>Q 10
An electric heater of 1000 W is used everyday for 70 minutes. Calculate the units of electrical energy this heater will consume in 30 days of use.
MEDIUM
9th CBSE
IMPORTANT
Secondary Physics>Chapter 5 - Work and Energy>EXERCISES>Q 11
A bag of wheat weighing 8 kg is lifted through a height of 12 m in 5 seconds with a constant velocity. Calculate the power developed during the process.
MEDIUM
9th CBSE
IMPORTANT
Secondary Physics>Chapter 5 - Work and Energy>EXERCISES>Q 12

A force of 200 N acting at an angle of 45° to the horizontal does a work of 45000 J. Calculate the displacement caused by the force in horizontal direction. (Take cos 45°=0 .7071)

HARD
9th CBSE
IMPORTANT
Secondary Physics>Chapter 5 - Work and Energy>EXERCISES>Q 1
Explain the term 'work'. Define and explain positive, negative and zero work by giving suitable examples.

 

HARD
9th CBSE
IMPORTANT
Secondary Physics>Chapter 5 - Work and Energy>EXERCISES>Q 2
Derive an expression for the kinetic energy of a body which starts from rest and acquires a velocity under the action of a constant force.