# Physics Work Energy And Power Problems And Solutions Pdf

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## NCERT Solutions for Class 11 Physics Chapter 6

Question 6. The sign of work done by a force on a body is important to understand. State carefully if the following quantities are positive or negative: a Work done by a man in lifting a bucket out of a well by means of a rope tied to the bucket, b Work done by gravitational force in the above case, c Work done by friction on a body sliding down an inclined plane, d Work done by an applied force on a body moving on a rough horizontal plane with uniform velocity, e Work done by the resistive force of air on a vibrating pendulum in bringing it to rest.

Compute the a Work done by the applied force in 10 s b Work done by friction in 10 s c Work done by the net force on the body in 10 s d Change in kinetic energy of the body in 10 s and interpret your results. Given figures are examples of some potential energy functions in one dimension.

The total energy of the particle is indicated by a cross on the ordinate axis. In each case, specify the regions, if any, in which the particle cannot be found for the given energy.

Also, indicate the minimum total energy the particle must have in each case. Think of some physical contexts for which these potential energy shapes are relevant. The object can not exist in the region, where its K.

So, kinetic energy is positive. So, kinetic energy will be negative in this region. The minimum total energy that the particle can have in this case is zero.

Thus object cannot be present in any region of the graph. The particle can not exist in these portions. Because in this region P. The particle can go up to a maximum distance x m , where its total energy is transformed into elastic potential energy. Answer the following: a The casing of a rocket in flight bums up due to friction. At whose expense is the heat energy required for burning obtained? The rocket or the atmosphere? Yet the work done by the gravitational force over every complete orbit of the comet is zero.

Why then does its speed increase progressively as it comes closer and closer to the earth? In Fig. The rope goes over a pulley, and a mass of 15 kg hangs at its other end.

In which case is the work done greater? As a result of work done against friction the kinetic energy of rocket continuously decreases — and this work against friction reappears as heat energy. As a result, kinetic energy of satellite slightly increases i. Thus, work done in ii case is greater. Answer: a Potential energy of the body decreases because the body in this case goes closer to the centre of the force. Hence the rate of change of total momentum of many particle system is proportional to the external force on the system.

State if each of the following statements is true or false. Give reasons for your answer. Friction is not a conservative force hence work done by force of friction or work done on the body against friction is not zero over a closed loop.

Answer carefully, with reasons: a In an elastic collision of two billiard balls, is the total kinetic energy conserved during the short time of collision of the balls i.

Note, we are talking here of potential energy corresponding to the force during collision, not gravitational potential energy. A body is initially at rest. It undergoes a one-dimensional motion with constant acceleration. A body is moving unidirectionally under the influence of a source of constant power. What is the work done by this force in moving the body a distance of 4 m along the z-axis?

An electron and a proton are detected in a cosmic ray experiment, the first with kinetic energy 10 keV, and the second with keV. Which is faster, the electron or the proton? A raindrop of radius 2 mm falls from a height of m above the ground.

It falls with decreasing acceleration due to viscous resistance of the air until at half its original height, it attains its maximum terminal speed, and moves with uniform speed thereafter. What is the work done by the gravitational force on the drop in the first and second half of its journey? What is the work done by the resistive force in the entire journey if its speed on reaching the ground is 10 ms -1? If there was no resistive forces, energy of drop on reaching the ground.

Is momentum conserved in the collision? Is the collision elastic or inelastic? The wall remains at rest due to its large mass. Resolving momentum of the molecule along x-axis and y-axis, we get The x-component of momentum of molecule.

A pump on the ground floor of a building can pump up water to fill a tank of volume 30 m 3 in 15 min. Two identical ball bearings in contact with each other and resting on a friction less table are hit head-on by another ball bearing of the same mass moving initially with a speed V.

If the collision is elastic, which of the following Fig. Before collision, total K. How high does the bob A rise after the collision? Neglect the size of the bobs and assume the collision to be elastic. The bob transfers its entire momentum to the ball on the table. The bob does not rise at all. The bob of a pendulum is released from a horizontal position. If the length of the pendulum is 1. What is the speed of the trolley after the entire sand bag is empty? Clearly, the system is not being acted upon by an external force.

If the sand leaks out, even then no external force acts. So there shall be no change in the speed of the trolley. A particle of mass 0. The blades of a windmill sweep out a circle of area A.

What is the electrical power produced? A person trying to lose weight dieter lifts a 10 kg mass, one thousand times, to a height of 0. Assume that the potential energy lost each time she lowers the mass is dissipated, a How much work does she do against the gravitational force? How much fat will the dieter use up? A family uses 8 kW of power, a Direct solar energy is incident on the horizontal surface at an average rate of W per square meter.

A bullet of mass 0. The block is suspended from the ceiling by thin wire. Calculate the height to which the block rises. Also, estimate the amount of heat produced in the block.

Let v be the velocity acquired by the combination. Two inclined frictionless tracks, one gradual and the other steep meet at A from where two stones are allowed to slide down from rest, one on each track Fig. Will the stones reach the bottom at the same time? Will they reach there at the same speed? A 1 kg block situated on a rough incline is connected to a spring with spring constant Nm -1 as shown in Figure. The block is released from rest with the spring in the unstretched position. The block moves 10 cm down the incline before coming to rest.

Find the coefficient of friction between the block and the incline. Assume that the spring has negligible mass and the pulley is frictionless. A bolt of mass 0. What is the heat produced by the impact?

Would your answer be different if the elevator were stationary? So the whole of the energy is converted into heat. Since the value of acceleration due to gravity is the same in all inertial system, therefore the answer will not change even if the elevator is stationary.

A trolley of mass kg moves with a uniform speed of 36 km h -1 on a friction less track. What is the final speed of the trolley? How much has the trolley moved from the time the child begins to run? He will observe the initial momentum of the trolley of mass M and child of mass m as zero.

Let u be the velocity of the child. Final speed of trolley is The child take 2. Which of the following potential energy curves in Fig. Here r is distance between centres of the balls. When the two billiard balls touch each other, P.

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Thanks for visiting our website. Our aim is to help students learn subjects like physics, maths and science for students in school , college and those preparing for competitive exams. All right reserved. All material given in this website is a property of physicscatalyst. A body fall from height H. Which of these relation is true for t 1 and t 2 a.

## Work and Power

Question 6. The sign of work done by a force on a body is important to understand. State carefully if the following quantities are positive or negative: a Work done by a man in lifting a bucket out of a well by means of a rope tied to the bucket, b Work done by gravitational force in the above case, c Work done by friction on a body sliding down an inclined plane, d Work done by an applied force on a body moving on a rough horizontal plane with uniform velocity, e Work done by the resistive force of air on a vibrating pendulum in bringing it to rest. Compute the a Work done by the applied force in 10 s b Work done by friction in 10 s c Work done by the net force on the body in 10 s d Change in kinetic energy of the body in 10 s and interpret your results. Given figures are examples of some potential energy functions in one dimension.

Get Free The Physics Classroom Work Energy And Power Worksheet Answers Dear subscriber, later than you are hunting the the physics classroom work energy and power worksheet answers store to get into this day, this can be your referred book. Calculate the work done by force. All important questions are listed with answer.

The first two subtopics explain the scalar product and the notions of work and kinetic energy. Additionally, the first part of Work, Energy and Power includes the work-energy theorem, the concept of kinetic energy, potential energy, conservation of mechanical energy, and much more. NCERT solutions Class 11th Physics Chapter 6 provides you with step-by-step solutions of Mathematical problems and detailed theoretical representation to help you grasp these concepts. NCERT solution of Physics Class 11 Chapter 6 in the next part explains the concept of power and collisions by providing lucid diagrammatic representations. But it takes a smart approach in providing you with in-depth theoretical knowledge by incorporating questions that require you to choose the correct alternative.

Да нет, - замялся.  - Я просто… - Сьюзан Флетчер.  - Женщина улыбнулась и протянула ему тонкую изящную руку.

- Этот парень был диссидентом, но диссидентом, сохранившим совесть.

Вы не скажете, где они могли остановиться. Клушар закрыл глаза, силы покинули. Он едва дышал. - Хоть что-нибудь, - настаивал Беккер.

Сеньор?. - Буисан, - сказал Беккер.  - Мигель Буисан. - Понятно. Она получит ваше письмо утром.

Бринкерхофф опрокинул директорский стул и бросился к двери. Он сразу же узнал этот голос. - Директор! - воскликнул он и, подойдя к Фонтейну, протянул руку.  - С возвращением, сэр.

Джабба открыл рот, готовый что-то сказать, но тут его буквально парализовал душераздирающий крик. Все повернули головы к Сьюзан Флетчер, которая выпрямилась и поднялась со стула. Лицо ее побелело, глаза не отрываясь смотрели на застывший кадр, демонстрировавший неподвижное тело Дэвида Беккера, залитое кровью, брошенное на пол мини-автобуса.

Что мешает ему сделать это еще. Но Танкадо… - размышляла .

Спальня, - без колебаний отозвался. Сьюзан смутилась. - Хорошо, а что, если… кошка.

Последний из трех миллионов процессоров размером с почтовую марку занял свое место, все программное обеспечение было установлено, и керамическая оболочка наглухо заделана. ТРАНСТЕКСТ появился на свет. Хотя создававшийся в обстановке повышенной секретности ТРАНСТЕКСТ стал плодом усилий многих умов и принцип его работы не был доступен ни одному человеку в отдельности, он, в сущности, был довольно прост: множество рук делают груз легким.

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