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Syllabus

derive relationship between commercial unit of energy and si unit of energy

if a force F is applied on a body and it moves with velocity v , the power will be :

^{2}^{2}is ncert solutions for computer science avalable

calculate the work required to be done to stop a car of 1500kg moving at a velocity of 60km/h?

A heavy stone is lowered on the ground. The work done is positive or negative.

Explain answer briefly.

Define 1 watt of power:a) its mass is tripled

b) its velocity becomes one-fourth

what is the relation between KW h and joules

What is the formula of sulphide ion,sulphate ion,sulphur ion ?

Q- Give one example of:-

A particle starts from rest at x=0 and moves to x=L, under the action of a variable force F(x) which is shown in figure. What is the kinetic energy of particles at x = L/2 & at x = L.

(a) Certain force acting on a 20kg mass changes its velocity from 5m /s to 2 m/s . calculate the work done by the force .

(b) State two possible condition under which the work done would be zero.

(c) if the kinetic energy of the body is increased by 300% then determine the percentage increase in the momentum.

give examples of the situations of work done and work not done (15-20)

the power of motor pump is 2kW. how much water per minute the pump can raise to a height of 10m? (given g = 10m/s)

suggest me a working science model for class 9th

In an oscillating pendulum, at what positions the potential and kinetic energy are maximum?

The kinetic energy of an object of mass , m moving with a velocity of 5m/s is 25J.what will be its kinetic energy when its velocity is doubled ?what will be its kinetic energy when its velocity is incrased three times

a body of mass 2 kg is thrown vertically upwards with the initial velocity of 20 m s

^{-1}. what will be its potential energy at the end of 2 seconds.(g=10m s^{-2})a) a working electric geyser

b)a glowing electric bulb

c)a working electric fan

d)burning cooking gas

e)a bullet fired from a gun

f)working engine of moving motor car

g)a swinging pendulum

h)a catapult just releasing a stone

What is the derivation of Kinetic energy and Potential energy

What is the work done to increase the velocity of a car from 30km/h to 60km/h if the mass of the car is 1500kg?

(a) While it is still on the tree.

(b) When it hits the bystander.

(c) When it bounces upto its maximum height.

(d) When it lands on the ground.

(e) When it rolls into a pit and falls 2.5 m deep inside.

the k

_{E }acquired by a mass m in travelling a certain distance s ,starting from rest ,under the action of a constant force is directly proportional to:a)

mb)/

mc)1//

md)none of theseQ1. The volume of 50g of a substance is 20cm3 . If the denstiy of water is 1 g cm3, will the substance float or sink in water ? justify your answer ?

Q2. Show that the energy of a vibrating pendulum is conserved ?

Q3. A ball is dropped from a heigh of 10m. If the energy of the ball reduces by 40% after striking the ground, how much high can the ball bounce back ?

a ball of mass 2kg is thrown up with a speed of 10m/s. find the kinetic energy of the ball at the time of throwing.also find its potential energy of the ball at the highest point.[g = 10m/s].define 1 watt of power?

c) What happens to the potential energy of a body, if its (1) height is doubled, (2) mass is increased by three times, (3) the body is taken of the surface of the Moon?

define work , its formula with SI unit ?

velocity of a body is increased by 5 times what happens to its kinetic energy?

define power. Give the SI unit of power

Derive an expression for the gravitational potential energy of an object of mass 'm' at a height 'h' above the earth's surface.

Force acting on a particle moving in a straight line varies with the velocity of the particle as F=k/v,where K is a constant.The work done by this force in time t is:

(A)K/v^2.t

(B)2Kt

(C)Kt

(D)2Kt/v^2

A stone projected vertically upward with a velocity 'u' reaches a maximum height 'h'. Find the ratio of kinetic energy and potential energy of the stone, when it is at height 3h/4 from the ground..?

which physical quantity has the S.I. unit = Nm or newton -metre

1. Can a body have energy without momentum ????

2. Can a body have momentum without energy ?????

plzz ans. with explanation ???

Identify and state the type of transformation of energy in the following cases:

1. When coal is burnt.

2. When a dry cell discharges.

3. In a thermal power plant.

i) position

ii) configuration of the body

Can any object have momentum even if its mechanical energy is 0? explain.

What is the work done by a satellite moving around the earth ?Justify your answer.

Q2)

Which of the following statements about the work done by a force is incorrect?

Work is done by a force only if a body moves towards the direction of the applied force.

Work done by a body is equal to the amount of energy gained or spent by the body.

Work done by a force can be zero even if the body moves to a certain distance.

Work done by a force can be positive as well as negative.

Ans :Work done by a force is defined as the product of the force on a body and the displacement of the body along the line of action of the force. Therefore,

This is because the displacement of the body is along the line of action of the applied force. In this case, the work done by the force is considered negative.it is not necessary that the body always moves towards the direction of the applied force. Even if a body moves opposite to the direction of the applied force, work is done by the applied force.The correct answer is A.

Dear Experts, I can't understand this. How can it be not necessary that an objectalways moves towards the direction of the applied force?

If the above is correct, then please coin an example.

A freely falling object eventually stops on reaching the ground. What happens to its kinetic energy

If the speed of a body is halved ,what will be the change in its kinetic energy??????????

plz answer

a mass of 3g is moving with a velocity of 18km/h.calculate kinetic energy of the body in joule.

why iron nail sinks and cork float on water?

A 5 kg cart is pushed by a 30 N force against friction for a distance of 10 m in 5 sec. Determine the power needed to move the cart.

I am confused as to how to find K.E. in the Activity 11.15 at Page 155 of Work and Energy chapter because we don't know the velocity in those cases. Finding P.E. is easy there. Can anybody help???

1 mg of uranium-235 is completely destroyed in an atomic bomb. how much energy is liberated? (ans: 9*10^10)

an electric heater is rated 1500w. how much energy does it use in 10 hrs.express your answer kwt and joules.

Topic:-Determination of the density of solid by using a spring balance and a measuring cylinder.

Also tell

Least count of spring balance(in g wt.)

Zero error of the spring balance(g wt)

Least count of measuring cylinder(mL).

Based on this plz complete the table attached.

Plz solve it as soon as possible.

wat is the relationship between JOULE (J) and ERG ??????experts answer ??:DDAn object of mass of 20 kg is dropped from a height of 4 m. Fill in the blanks in the following table by computing the potential energy and kinetic energy in each case.

height at which object is located: 4 m, 3 m, 2m, 1m, just above the ground

Potential energy

Kinetic energy

(for simplifying the calculations, take the value of g as 10 m s

^{-2})derive an expression for kinetic energy of a body ?

A block of mass 2 kg is lying on the frictionless table. A force of 8N is applied on it for 12 seconds. Calculate its Kinetic Energy.

State the relation between commercial unit of energy and joules .!How much work is done on a body of mass 1kg whirling on a path of radius 5m ?If an object is immersed wholly in a liquid causing upthrust equal to the weight of the body then what will be the relation between the relative densities of liquid and the object ?When do we say that work is done?

(a) DID THE OLD MAN DO ANY WORK WHILE HOLDING THE LUGGAGE?

(b) WHAT IS THE EQUATION FOR WORK DONE AGAINST GRAVITY?

(c) WHY DID SAURABH ASK THE OLD MAN TO PUT DOWN THE LUGGAGE?

Explain the transformation of energy in hydroelectric power plant?

can you plz give me the examples of kinetic energy?????????????

1. when is work done by a force zero?.

2.Moon is experiencing a gravitational force due to earth and it is revolving around the earth by an circular orbit. How much work is done by the moon ?

3. What is the work done against gravity when a body is moving horizondally along a frictionless surface. What is the work done against gravity ?

4. A ball is thrown vertically up what happens its potential energy when becomes zero?

5. If the speed of the body is half what is the change in the kinetic energy?

6. A 2m height person holding 25 kg trunk on his head is standing at road ways bus stop. How much work is done by him?

7. If hard works 60J in 1m . What is its power ?

8. Calculate the work done when a force of 15N moves a body by 5m in its direction .

9. what will be the kinetic energy of a body when its mass is made 4 times and velocity is doubled.?

10. IN an office a tube light of 40W, a fan of 75W and a cooler of 150W, all applicance are used 8hrs a day. Calculate the energy consumed per day in commercial unit of energy.

11. 4 persons jointly lift 350kg box to a height of 1m and holding it

(a) calculate the work done in lifting the box.

( b) how much work they do in holding it .

(c) why do they get tired while holding it.

12. The potential enrgy of a freely falling object decreasing gradually.

(a) Does it voilate law of conservation of energy.

(b) An object is dropped from a height (h)

a. When is it potential energy maximum?

b. When is it kinetic energy maximum?

13. A boy of mass 45kg climbs up 20 steps in 20sec. If each step is 25cm height calculate the power of the boy used in climbing (G=10)

14. State the law of conservation of energy.

Explain with the help of a simple pentulum. Illustrate if nessesary .

15. A mass of 10kg is droped from a height 50cm. Find its :

(a) potential energy just before dropping

(b) kinetic energy just on touching the ground

(c) velocity with which it hits the ground.

16. Can any object have momentum evenif its machanical energy is zero.

(a) a ball is droped from a height 10m

(b) if energy of the ball is reduced by 40% after stricking the ground.

Water is falling on the Blades of a turbine at the rate of 6 * 10

^{3 kg per minure .}The height of the fall is 10 m . Claculate the power given to the turbine. Take g = 10 m/s

^{2}what is the proof for w = F S cos theta

a truck and a car moving with same kinetic energy are stopped by applying same retarding force by means of brakes. which stops at a smaller distance?

define density?Give its SIunit.

1. A block of 20 kg is pulled up by applying a force acting parallel to the slope. If the slope makes an angle of 30 degree with the horizontal, calculate the work done in pulling the load by a distance of 3m. What is the increase in potential energy of the block. (g = 10 newton per kg)

2. The speed of a bicycle decreases from 18 to 9 kmph. If the total mass of cyclist including the cycle is 70 kg, calculate the work done in overcoming the friction offered by the brakes & the road. Does the kinetic energy of the system also reduce to half its initial value?

a man drops 10kg rock from the top of a 5m ladder. wht is its speed just before it hits the ground? wht is its kinetic energy wen it reaches da ground.

a moving body of mass 30 kg has 60 joules of K.E. calculate its speed.

Derive the relation between momentum and kinetic energy ??????

examples of kinetic enery and potential energy its urgent

Water stored in a dam possesses

(a) no energy (b) electrical energy (c) kinetic energy (d) potential energy

THE LEANING TOWER OF PISA IS 45m HIGH . A MASS OF 4kg IS DROPPED FROM TOP . CALCULATE :

a}THE POTENTIAL ENERGY AT THE TOP

b}THE KINETIC ENERGY JUST BEFORE HITTING THE GROUND

c}THE VELOCITY JUST BEFORE HOTTONG THE GROUND

Derive an expression for the kinetic energy of an object of mass 'm' moving horizontally with a uniform velocity 'v'

two bodies of masses (m1) and (m2) have equal kinetic energy. what shall be the ratio of their momentum

prove that the energy remains constant in case of a freely falling body....

When a body is projected vertically up from the ground, its potential energy and kinetic energy at a point P are in the ratio 1:5. If same body is projected with half the pervious velocity, then at the same point P, ratio of its potential energy and kinetic energy would be

A. 1 : 2

B. 2 : 1

C. 1 : 5

D. 2 : 5

An object of mass 40kg is raised to a height of 5m above the ground.What is its PE?If the object is allowed to fall,find its KE when it is half way downAn object of mass 40 kg is raised to a height of 5m above the ground.What is its PE?If the object is allowed to fall,find its KE when it is half way down

A boy of mass 55 kg runs up a flight of 40 stairs each measuring 0.15m. Calculate the work done by the boy?

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define average power