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Work and energy test b answers

# Work and energy test b answers

In order for work to take place, there is an amount of energy that has to be used. Work can either change the kinetic energy or change the potential energy. Do you understand the connection between work and energy?

Test how well you understood the topic by taking up the quiz below. All the best and keep a lookout for more tests on the topic. Work is the what you get when a force acts over a certain distance. Therefore, without distance or force there would be no work. GPE is potential energy that's dependent on height, EPE is energy associated with objects that can be stretched or compressed. GPE is potential energy dependent on weight only, and EPE is the potential energy only found in rubber bands.

Forgot your password? Speak now. Work And Energy Quiz. Please take the quiz to rate it. All questions 5 questions 6 questions 7 questions 8 questions 9 questions 10 questions 11 questions 12 questions. Feedback During the Quiz End of Quiz. Play as Quiz Flashcard. Title of New Duplicated Quiz:. Duplicate Quiz Cancel. More Work And Energy Quizzes.

Test: Work, Energy And Power. Featured Quizzes. Are You A Sociopath? Related Topics. Questions and Answers. Remove Excerpt. Removing question excerpt is a premium feature. Work and Distance are related because force is acted over a long distance. What are the units for work? If you exert a force of newtons, and the object moves 10 meters how much work did you do? What is Energy, and how does it relate to work?

Energy is the ability to do work or make work, and without it work not is done. Energy is the ability to do work or cause a change, and work is the transfer of energy.ANSWER: is always constant Explanation: The system in which both the mass as well as energy cannot be transferred between system and its surrounding is called as isolated system.

As the energy can neither be transmitted nor be absorbed, the total energy of an isolated system is always constant.

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Temperature is the term through which we can differentiate between hot and cold. When two bodies are brought in physical contact with each other and one body has more temperature than other then hear transfer takes place from hot body to cold one. After some time they attain a common temperature and then they are in a thermal equilibrium. These phenomena are very important in thermodynamics.

In thermodynamics, work transfer occurs between system and surrounding. Work is said to be done by a system when the energy is transferred from the system and it is responsible for or counted as some external mechanical change. When work is done by a system then it is taken as positive, and when work is done on the system by the surrounding then it is taken as negative. The symbol W is used for work transfer. ANSWER: the internal energy of the system increases Explanation: When a system undergoes cycle, then the algebraic sum of all energy transfer across the boundaries is zero.

But when a system undergoes a change of state in which both heat transfer and work transfer are involved, the net energy transfer is stored and collected within the system. If Q is the amount of heat transferred to the system and W is the amount of work transferred from the system during the process, then the net energy Q — W is stored in the system. This energy is neither heat nor work but it is called as internal energy.

For example, according to Joule, based on his experiments, energy supplied to a system in a form of heat, can be completely converted into work. But this process is not possible, because we know that in thermodynamic process internal energy of a system also increases. Thus, Heat transfer — Internal energy increase — Work transfer The complete conversion of heat into work is not possible.

Therefore heat and work are not completely interchangeable forms of energy. ANSWER: a statement that energy balance occurs when a system undergoes the change of state or the process Explanation: The first law of thermodynamics states that the energy balance occurs when a system undergoes the change of state or the process. It states that if energy is supplied to a system in a form of heat, which can be completely converted into work energy. But practically it is not possible, because internal energy of the system also increases in the process.

Thus, first law of thermodynamics does not provide information on whether the change of state or the process is feasible or not. Consider the following heat engine, The heat Q1 is transferred to the system and work W1 is done by the system.

Then system is taken to its initial position by applying work W2 on the piston and heat Q2 is rejected from the system. This is the heat engine cycle. In heat engine cycle, a net heat is transferred to the system and a net work is transferred from the system. ANSWER: refrigerator Explanation: In heat engine cycle, a net heat is transferred to the system and a net work is transferred from the system. In the system of mass of gas confined in a cylinder and piston machine, the heat is added to the system and work is done by the system on the piston and vice versa.

In stem power plant initially the heat is added from the furnace to boiler, this stem passes through the turbine and work is done, then the stem is condensed to water in condenser and the heat is rejected from the system, and finally work is done on the system to pump the water back to the boiler.

But refrigerator does not consist heat engine cycle, because in refrigerator, the work is done on the system and heat transfer takes place from the system. ANSWER: total heat input to the cycle Q in to net work output of the cycle W net Explanation: In heat engine cycle, the heat is transferred to the system and work is transferred from the system. The main function of heat engine is to produce work output continuously by consuming heat energy given to the system.

So the net work W net and heat supplied Q in to the system are taken into account. The net work output is the difference between work produces in the process and the work input required to take the system to initial state.

In stem power plant, net work output is, Turbine Work W T — Pump Work W P Therefore, the efficiency of heat engine cycle is the ratio of total heat input to the cycle Q in to net work output of the cycle W net. ANSWER: an infinite heat capacity Explanation: A thermal energy reservoir has a capacity of absorbing or rejecting an unlimited amount of heat without considerable change in its temperature. These are the large bodies, in which the heat enters or leaves are very slow and very minute.

Heat capacity is the product of mass of the body and specific heat of the body.

As the thermal energy reservoirs are the large bodies, their heat capacity will be infinite.In order for work to take place, there is an amount of energy that has to be used. Work can either change the kinetic energy or change the potential energy.

Do you understand the connection between work and energy? Test how well you understood the topic by taking up the quiz below. All the best and keep a lookout for more tests on the topic. Work is the what you get when a force acts over a certain distance. Therefore, without distance or force there would be no work. GPE is potential energy that's dependent on height, EPE is energy associated with objects that can be stretched or compressed.

GPE is potential energy dependent on weight only, and EPE is the potential energy only found in rubber bands. Forgot your password? Speak now. Work And Energy Quiz. Please take the quiz to rate it. All questions 5 questions 6 questions 7 questions 8 questions 9 questions 10 questions 11 questions 12 questions.

Feedback During the Quiz End of Quiz. Play as Quiz Flashcard. Title of New Duplicated Quiz:. Duplicate Quiz Cancel. More Work And Energy Quizzes. Test: Work, Energy And Power. Featured Quizzes.Energy transfer is needed in order to make things work.

When answering questions on this topic, you will need to know:. You will be required to recall most of the equations needed to carry out the calculations for this topic, and rearrange them as necessary.

With multiple-choice questions like this, be careful to tick the correct number of boxes — in this case, just one. If you tick more than the specified number, you will get no marks. For example, in this question, it is unlikely that turbines off shore are easier to maintain than those on land.

Note that nuclear fuel, i. Solar panels will not provide a consistent supply of energy as the coal power station does. The amount of energy supplied by the solar panels per hour will be much lower than the amount supplied by the coal power station. Be careful — it is very easy to give one reason and then move onto the next question. Calculate the number of wind turbines needed to meet the needs of the group of factories.

You would get 2 marks for a correct answer with no working shown. However, it is advisable to always show your working — that way, if you make an error and give the wrong answer, you may still pick up marks for your method.

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In this question, showing that the total power is divided by the power of each wind turbine would earn you 1 mark. The table contains information about the two solar panels on top of the Jungfraujoch Observatory in Switzerland.

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How does this data support the claim that solar panels are becoming more efficient over time? To answer this question, you need to select the relevant information from the given data.

If you state that Panel A is more efficient, you will only gain 1 mark. As the question is about efficiency improving over time, you must make reference to the dates to gain the second mark. For example:.The concept of work in physics is much more narrowly defined than the common use of the word.

Work is done on an object when an applied force moves it through a distance. In our everyday language, work is related to expenditure of muscular effort, but this is not the case in the language of physics. A person that holds a heavy object does no physical work because the force is not moving the object through a distance. Work, according to the physics definition, is being accomplished while the heavy object is being lifted but not while the object is stationary. Another example of the absence of work is a mass on the end of a string rotating in a horizontal circle on a frictionless surface.

The centripetal force is directed toward the center of the circle and, therefore, is not moving the object through a distance; that is, the force is not in the direction of motion of the object. However, work was done to set the mass in motion. Work is a scalar.

### Work and Energy-MCQ

If work is done by a varying force, the above equation cannot be used. The work performed on the object by each force is the area between the curve and the x axis. The total work done is the total area between the curve and the x axis. For example, in this case, the work done by the three successive forces is shown in Figure 1. Acting force changing with position. Kinetic energy. Kinetic energy is the energy of an object in motion. The expression for kinetic energy can be derived from the definition for work and from kinematic relationships.

Consider a force applied parallel to the surface that moves an object with constant acceleration.

Quiz on "Work Energy and Power" - LIVE Online Quiz - Abhishek Sir - Vedantu class 9

The right side of the last equation yields the definition for kinetic energy: K. The above derivation shows that the net work is equal to the change in kinetic energy. Potential energy.

Potential energy, also referred to as stored energy, is the ability of a system to do work due to its position or internal structure. Examples are energy stored in a pile driver at the top of its path or energy stored in a coiled spring. Potential energy is measured in units of joules. Gravitational potential energy is energy of position.

First, consider gravitational potential energy near the surface of the earth where the acceleration due to gravity g is approximately constant. In this case, an object's gravitational potential energy with respect to some reference level is P. To lift an object slowly, a force equal to its weight mg is applied through a height h. Launching a rocket into space requires work to separate the mass of the earth and the rocket to overcome the gravitational force.

For large distances from the center of the earth, the above equation is inadequate because g is not constant. The general form of gravitational potential energy is P. The negative sign is a result of selecting the zero reference at r equal to infinity, that is, at very large separation. Elastic potential energy is energy stored in a spring.

The spring constant is a measure of the stiffness of the spring, with stiffer springs having larger k values. The potential energy stored in a spring is given by P.In the picture given above F pulls a box having 4kg mass from point A to B. If the friction constant between surface and box is 0,3; find the work done by F, work done by friction force and work done by resultant force.

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Applied force vs. Find the work done by the forces on the object. Different forces are applied to three objects having equal masses. Forces pull objects to height h. Find the work done by the forces on objects and work done on gravity. Since masses of the objects are equal, and distance taken by the objects are equal, work done on gravity of three objects are equal.

In the picture given below, forces act on objects. Works done on objects during time t are W 1W 2 and W 3. Find the relation of the works. Horizontal components of the applied forces are equal to each other. Masses of the objects are also equal.

### Work and energy questions

Thus, acceleration of the objects and distances taken are also equal. A box having 2 kg mass, under the effect of forces F 1F 2 and F 3takes distance 5m. Which ones of the forces do work. Tags: work power energy calculations work power energy exam questions and answers work power energy samples work problems and solutions. Additional Information.Questions pertain to the analysis of motion using relationships related to work and energy, mainly energy conservation and work-energy transfer principles.

The following concepts are emphasized: work, positive work, negative work, energy, power, conservative internal forces, non-conservative external forces, potential energy, kinetic energy, mechanical energy, conservation of energy, work-energy theorem, pendulum, and incline planes.

Powerful people or powerful machines are simply people or machines which always do a lot of work. If person A and person B do the same job but person B does it faster, then person A does more work but person B has more power.

## Chapter Test : Work, Energy And Power

Physicists envy biologists' ability to instill order on the world of animal species through their taxonomic system. So physicists have made a habit of identifying forces as conservative and non-conservative forces in order to instill order on the world of forces.

A force is regarded as a non-conservative force if it does not add mechanical energy to a system of objects. The total amount of mechanical energy of an object is the sum of its potential energy and the kinetic energy. The force on the car causing it to stop is applied at the only point of contact the car has -- the ground!

The ground pushes on the car opposite to the car's motion that's the meaning of the minus sign abovecausing it to stop. You can tell this, because a car's tires get hot from the friction forces between them and the road.

The KE of the cars motion is turned into heat energy the car's tires, the brakes and the road get hot so the work done on the car is not recoverable.

F work is done on an object by a non-conservative force, then the object will either gain or lose kinetic energy. Technically no, the work done is not increasing the potential energy, it is decreasing it! We haven't converted energy into a form that we can tap into again.

An object has a kinetic energy of 40 J. If its mass were twice as much, then its kinetic energy would be 80 J. Faster moving objects would have more kinetic energy than other objects of the same mass. However, another object could have less speed and make up for this lack of speed in terms of a greater mass. When the car moves with constant velocity, its acceleration is zero.

By Newton's second law, this means that the net force is zero. More massive objects would have more kinetic energy than other objects with the same speed. However, another object could have less mass and make up for this lack of mass in terms of a greater speed.

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The total work is the work done by the net force. After 50 m, the car moves with constant velocity so the net force is zero. This means that the total work done on the car after 50 m is zero.