Physics Project WorkTopic – Work and Energy

Shalini Arya Class – 9th

Rollno- 19 In the guidance Of- Mr. Ashutosh Pandey Sir

Forms of energy1. Mechanical energy (Kinetic

energy + Potential energy2. Heat energy3. Chemical energy4. Electrical energy5. Light energy

Commercial unit of energy

Machine is used continuously for one hour, itWill consume 1 kWh of energy. Thus, 1 kWh is the energy used in one hour at the rate of 1000J s/1 or (1kW) 1kWh=3.6 . 10 power 6 J.

Formula

1. Kinetic energy= ½ mv square.2. Potential energy= mgh

Work can be positive or negative

• Man does positive work lifting box

• Man does negative work lowering box

• Gravity does positive work when box lowers

• Gravity does negative work when box is raised

Power

The rate of doing work or work done per Unit time is called power.

Power• Power is rate of energy transfer

P W

t

• SI units are Watts (W)

1 W 1 J / s 1 kgm2

s3

• US Customary units are hp (horse power)

1 hp 550 ft lb/s 746 W

QuestionsA. It is necessary to do the work-1.A force is acting on the object2.Object is displaced3.A force is acted on the object and it is displaced4.All of above

Answer- 3

B. An object on height possesses-

1. Kinetic energy2. Potential energy3. Potential as well as

kinetic energy both4. It has no

relationship with energy

Answer- 2

C. A fly bird possesses-

1.Potential energy2.Kinetic energy3.Potential as well as kinetic energy both4.It has no relationship with energy

Answer- 3

D. Nm is the unit of-1. Force2. Work3. Power4. acceleration

Answer- 2

E. The other name of Nm is-

1.Hertz2.Erg3.Coulomb4.joule

Answer-4

F. The formula to calculate work is-

1.W= force/distance2.W=distance/force3.W= force . Distance4.All the above

Answer-3

G. The vector quantity is-

1. Energy2. Potential energy3. Kinetic energy 4. None of theseAnswer-4

H. 1 kWh is equal to

1. 6.3 . 10 power 6 J2. 3.6 . 10 power 6 J3. 3.6 . 10 power 3 J4. 6.3 . 10 power 3 J

Answer-2

I. Which of the following is not the unit of energy-1.Newton meter2.Joule3.Kilowatt hours4.kilowatt

Answer-4

J. Watt second is the unit of-1. Power2. Energy3. Light4. None of the above

Answer-2

Thankyou for Watching