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Syllabus

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

a metre scale of mass 100g is pivoted at one end . if it is held at 30 degree with the horizontal what is the potential energy associated with it?

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 body moving in a straight line at 72kmph undergoes an acceleration of 4m/s

^{2}. Find its speed after 2 seconds.Define 1 watt of power:what is the relation between KW h and joules

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

^{2}^{2}What is the formula of sulphide ion,sulphate ion,sulphur ion ?

Q- Give one example of:-

(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.

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

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

think of some situations in your daily life in daily work, list them. is work done in each situation, if work is done. which is the force acting on the object . what is the object on which the work is done. what happens to the object on which work is done.

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

The potential energy of a freely falling object decreases progressively. What happens to its (i) kinetic energy (ii) total mechanical energy? State the law on which your answer is based.

A household consumes 1 kWh of energy per day. How much energy is this in joule?

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})What is the derivation of Kinetic energy and Potential energy

Which of the following is carried by the waves from one place to another:

a) mass b) velocity c) wavelenght d) 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?

renatta gass is out with her friends.misfortune occurs and renetta and her friends find themselves getting a workout.they apply a cumulative force of 1080 N to push the car 218 m to the nearest fuel station.determine the workdoneon the car.

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 these1. Can a body have energy without momentum ????

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

plzz ans. with explanation ???

Q1. 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 ?

define 1 watt of power?

define work , its formula with SI unit ?

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.

define power. Give the SI unit of power

A bullet when fired at a target with a velocity of 100 m/sec penetrates one metre into it . if the bullet is fired at a similar target with a thickness 0.5 metre, then it will emerge from it with avelocity of___ m/s.

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

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..?

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. zero

b. would increase

c. would decrease

d. remains fixed

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.

what is the proof for w = F S cos theta

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

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

(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.

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

why iron nail sinks and cork float on water?

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.

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???

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

_{0}at an angle θ with the horizontal in a uniform gravitational field. The rate of work done (P) by the gravitational force plotted against time (t) will be aswat is the relationship between JOULE (J) and ERG ??????experts answer ??:DDstate & explain the law of conservation of energy with an example 2. explain how total energy a swinging pendulam at any instant of time remains conserved illustrate your answer with the help of Lbelled diagram

derive an expression for kinetic energy of a body ?

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 ?(1) A real image at 8 cm (2) A virtual image at 8 cm

(3) A real image at 4.8 cm (4) A virtual image at 4.8 cm

Q3. In a medium of refractive index 1.6 and having a convex surface has a point object in it at a distance of 12 cm from the pole. The radius of curvature is 6 cm. Locate the image as seen from air.

(1) A real image at 30 cm (2) A virtual image at 30 cm

(3) A real image at 4.28 cm (4) A virtual image at 4.28 cm

When do we say that work is done?

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].An 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})can you plz give me the examples of kinetic energy?????????????

Two bodies of different masses m1 and m2 (m1>m2) have same kinetic energy . They are stopped by applying some retarding force . Which body will stop first ?

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}(a) In a tug of war, one team (team A) wins and the other team (team B) loses. Which of these two teams does positive and negative work?

(b) What is the work done in case of a satellite moving around the earth?

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

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.

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.

Explain the transformation of energy in hydroelectric power plant?

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

When a body of mass 'm' revolves with uniform speed of 'v' on a circular path of radius 'r',the work done by the body in one complete rotation is

a) (1 / 2 ) mv

^{2}b) 2π rmv^{2}c) ( 2π - 0.5 ) mv^{2}d) 0examples of kinetic enery and potential energy its urgent

Prove that kinetic energy =p

^{2}/2mWater stored in a dam possesses

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

Name the devices or machines which convert (1) Chemical Energy into Heat Energy (2) Light Energy into Heat Energy (3) Heat Energy into Kinetic Energy. What must be the power of the brakes of a car for them to stop the car moving at a velocity of 60 km per hour , weighing 1500 kg?

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....

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

define average power

An engine pulls a car of mass 1500kg on a level road at constant speed of 5m/s.If the frictional force is 500N,what power does the engine generate?