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Question 1. Asked on :05 February 2019:05:47:19 PM

#### A body of mass 4kg is taken for a height of 5m to a height 10m. Find the increase in Potential Energy

-Added by Harshita Rathore Science » Work And Energy

Shalu Shukla

➧ Potential energy = mgh

➧ m = 4kg

➧ g = 10 m/s²

➧ Initial potential energy

➾ m g 5

➧ Final potential energy

➾ m g 10

➧ Change =

Final potential energy - Initial Potential

Energy

➾ mg 10 - mg 5

➾ mg (10 -5)

➾ 5 x m x g

➾ 5 x 4 x 10

➾ 200 J

-Answered by Shalu Shukla On 11 February 2019:05:52:18 PM

Question 2. Asked on :20 January 2019:11:04:33 AM

#### Define a negative, positive and zero.

-Added by Prince Rawat Science » Work And Energy

Himanshi Verma

Actually, zero is neither a negative or a positive number. The whole idea ofpositive and negative is defined in terms of zeroNegative numbers are numbers that are smaller than zero, and positive numbers are numbers that are bigger thanzero.

-Answered by Himanshi Verma On 20 January 2019:04:18:58 PM

Question 3. Asked on :20 January 2019:11:01:56 AM

#### Define law of conservation of energy.

-Added by Prince Rawat Science » Work And Energy

Himanshi Verma

जब उर्जा का एक रूप उर्जा के दुसरे रूप में रूपांतरित होता है तब कुल उर्जा की मात्रा अचार रहती है

1.उर्जा की न तो उत्पती हो सकती हल और न ही विनाश

2.बल्कि उर्जा रूपांतर के दौरान कुछ उर्जा बेकार हो जाती है लेकिन निकाय की कुल उर्जा आवर्तित रहती है|

-Answered by Himanshi Verma On 20 January 2019:04:19:28 PM

Question 4. Asked on :20 January 2019:11:00:15 AM

#### How many joules are there in 1 kilowatt hours.

-Added by Prince Rawat Science » Work And Energy

Himanshi Verma

1000 joules

-Answered by Himanshi Verma On 20 January 2019:04:22:17 PM

Question 5. Asked on :20 January 2019:10:24:57 AM

#### The power of an electric heater is 1500 watt. How much energy it consumed in 10 hours.

-Added by Rohit Rajput Science » Work And Energy

Himanshi Verma

Watt = 1500(w)

Taken time = 10 hours

power of an electric heated is =

= 15001000 = 1.5kw

t = 10 hours

Energy = power × Taken time

= 1.5 kw × 10 h

= 15kwh

-Answered by Himanshi Verma On 20 January 2019:04:22:55 PM

Question 6. Asked on :20 January 2019:10:21:52 AM

#### Five electric fans of 120 watts each are used for 4 hour. calculate the electrical energy consumed in Kilowatt hours.

-Added by Rohit Rajput Science » Work And Energy

Himanshi Verma

Five electric fans of watt = 120×5

= 600(W)

taken time = 4 hours

power of fans = 600(W)=

= 6001000 kw

=0.6kw

energy = power × taken time

= 0.6kw × 4h

= 2.4kwh.

-Answered by Himanshi Verma On 20 January 2019:04:23:20 PM

Question 7. Asked on :13 January 2019:11:27:09 AM

#### A machine lift up of weight of 50kg at the height of 25m in 10min. calculate the work done and also calculate the power of machine?

-Added by Himanshi Verma Science » Work And Energy

Akki chauhan

Mass = 50kg ,   height= 25m

work done = mg×h

=50×10×25

=12500 joule

Time= 10min

change into sec = 10×60

=600 sec

power of the machine= work done Time

= 12500600 = 2.08333 watt

-Answered by Akki chauhan On 15 January 2019:09:48:56 AM

Question 8. Asked on :12 January 2019:05:42:22 PM

#### Define potential and kinetic energy and also write its SI unit.

-Added by Himanshi Verma Science » Work And Energy

Akki chauhan

Kinetic energy : The energy possessed by an object due to its state of motion is called Kinetic energy

The S.I unit is Joule.

Potential energy : The energy of body due to its position or change in shape is known as potential energy.

The S.I unit is Joule.

-Answered by Akki chauhan On 13 January 2019:11:28:46 AM

Question 9. Asked on :12 January 2019:10:37:10 AM

#### A coolie carries luggage of a passenger along a long platform at a railway station. Has he done work on the luggage ? why?

-Added by Akki chauhan Science » Work And Energy

Akki chauhan

He has work done work because a coolie carries luggage along a long platform and there is displacement so, here  work is done.

-Answered by Akki chauhan On 14 January 2019:09:55:33 AM

Question 10. Asked on :12 January 2019:10:35:16 AM

#### Speed of a particle is doubled. What will be its new kinetic energy?

-Added by Akki chauhan Science » Work And Energy

Rohit Rajput

Four times of its initial value of kinetic energy.

-Answered by Rohit Rajput On 12 January 2019:10:37:14 AM

Question 11. Asked on :12 January 2019:10:34:10 AM

#### Name four forms of energy other then mechanical energy

-Added by Akki chauhan Science » Work And Energy

Akki chauhan

The four forms of energy are as follows:-

1. Kinetic Energy                       2. Potential Energy

3. Light Energy                          4. Electrical Energy

and, 5. Solar Energy

-Answered by Akki chauhan On 14 January 2019:09:55:11 AM

Question 12. Asked on :12 January 2019:10:27:48 AM

#### State the relation between KWH and joule

-Added by Akki chauhan Science » Work And Energy

Akki chauhan

Himanshi Verma

The relation between kilowatt hour and and joule is

1KWH =3600000 Joule

and   1KWH=3.6Mj (Mega Joule )

OR

We Know that KWH is a commercial unit 1KWH=1KW*1H

1000W*1H

1Watt*sec =1Joule

1KWH=3600000 joule

-Answered by Akki chauhan On 14 January 2019:09:54:46 AM

Question 13. Asked on :12 January 2019:10:26:56 AM

#### What do you mean by negative work ? Give its example.

-Added by Akki chauhan Science » Work And Energy

Akki chauhan

Work is said to be negative if force is acting opposite to the displacement.

Examples= 1. Work done by a man while descending through   a staircase is negative. Man applies a force in vertically upward direction to balance his weight but displacement is in downward direction and work is negative.

2. Work done by force of friction on moving vehicles is negative.

-Answered by Akki chauhan On 15 January 2019:08:40:30 AM

Question 14. Asked on :12 January 2019:10:24:21 AM

#### What do you mean by positive work? Give two example in support.

-Added by Akki chauhan Science » Work And Energy

Rohit Rajput
Work is said to be positive when force applied and the resulting displacement both are along the same direction.

Example: (i) A person climbing upward on a ladder (or staircase) does positive work against the force of gravity.

(ii) work done by horse while pulling a cart is positive work against the force of friction.

-Answered by Rohit Rajput On 12 January 2019:10:30:14 AM

Question 15. Asked on :12 January 2019:10:22:37 AM

#### What are the conditions for work can be zero

-Added by Akki chauhan Science » Work And Energy

Akki chauhan

The conditions for work done can be zero are as follows

1. There is no net force applied to the object.

2. Force is being applied but it does not cause any displacement.

-Answered by Akki chauhan On 14 January 2019:09:53:57 AM

Question 16. Asked on :12 January 2019:09:16:39 AM

#### Define the term work and energy .Write their S.I units?

-Added by Akki chauhan Science » Work And Energy

Akki chauhan

Energy : The capacity of doing work is known as energy . its S.I unit is joule.

Work :

-Answered by Akki chauhan On 12 January 2019:10:17:03 AM

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