Flowing water has the capacity to do work:
- ATrue
- BFalse
- CBoth
- DNone
Question types
Work And Energy question types
449 questions across 8 question groups — pick any mix to generate a Science paper with step-by-step answer keys.
449
Questions
8
Question groups
5
Question types
01
M.C.Q. [1 M]
183 Q→02Fill in the blank
11 Q→03true or false
5 Q→04One word answer.
70 Q→05Que-Ans (Each of 2 Mark )
116 Q→06Que-Ans (Each of 3 Mark )
45 Q→07Que-Ans (Each of 4 Mark )
14 Q→08Case study ( 4 Marks )
5 Q→Sample Questions
Work And Energy questions
One sample from each question group in this chapter. Select any group above to see the full set with answer keys.
What is the unit of measurement for work?
- AMeters
- BNewtons
- Cm/s
- DJoules
Does the Law of Conservation of energy apply to machines?
- ANo, as machines require a constant input of energy in order to work
- BYes, the energy required to maintain motion is balanced by the energy lost to friction
- CYes, but only to perpetual motion machines
- DNo, as the law would apply to only perpetual motion machines
A ball rolling on the ground possesses:
- AKinetic energy
- BPotential energy
- CNo energy
- DHeat energy
Which of the following physical quantities is different from others?
- AWork
- BKinetic energy
- CForce
- DPotential energy
One calorie = __________ joules. (4.184, 100, 10)
The ability of a body to do work is called Energy. The ability of a body to do work because of its motion is called __________. (Energy, Work, kinetic Energy)
The work done on a body moving in a circular path is __________. (Zero, Maximum, Minimum)
The electricity meter installed in our home measures electric energy in the units of __________. (Watt, Joule, kWh)
One joule = __________ erg. (10³, 10⁷, 10⁶)
The potential energy of a body of mass 1kg kept at a height of 1m is 1J?
Work done by gravity on a man moving on horizontal surface is negative.
No, matter what is the magnitude of mass falling from a height, its acceleration is always the same.
Kinetic energy + Potential energy = Mechanical energy.
Energy does not remain conserved in an oscillating pendulum.
Define average power.
Define 1 watt of power.
What is power?
Write an expression for the kinetic energy of an object.
What is the kinetic energy of an object?
A lamp consumes 1000J of electrical energy in 10s. What is its power?
A pair of bullocks exerts a force of 140N on a plough. The field being ploughed is 15m long. How much work is done in ploughing the length of the field?
A force of 7 N acts on an object. The displacement is, say 8 m , in the direction of the force Fig. . Let us take it that the force acts on the object through the displacement. What is the work done in this case?
A certain household has consumed 250 units of energy during a month. How much energy is this in joules?
Does the transfer of energy take place when you push a huge rock with all your might and fail to move it? Where is the energy you spend going?
A boy of mass 50kg runs up a staircase of 45 steps in 9s. If the height of each step is 15cm, then find the his power. (Take, g = 10-2ms)
Two girls, each of weight 400 N climb up a rope through a height of 8 m. We name one of the girls A and the other B. Girl A takes 20 s while B takes 50 s to accomplish this task. What is the power expended by each girl?
What is the work to be d to increase the velocity of a car f $30 km h ^{-1}$ to $60 km h ^{-1}$ if the mas the car is 1500 kg ?
View full solution →Is it possible that an object is in the state of accelerated motion due to external force acting on it, but no work is being done by the force. Explain it with an example.
A body of mass 2kg is thrown vertically upwards with an initial velocity of 20m/s. What will be its potential energy at the end of 2s? (Assume g = 10m/s2).
Two objects having equal masses are moving with uniform velocities of 2m/s and 6m/s respectively. Calculate the ratio of their kinetic energies.
On a level road, a scooterist applies brakes to slow down from a speed of 10m/s to 5m/s. If the mass of the scooterist and the scooter be 150kg, calculate the work done by the brakes. (Neglect air resistance and friction)
Calculate the work done by the brakes of a car of mass 1000kg when its speed is reduced from 20m/s to 10m/s?
A light and a heavy object have the same momentum. Find out the ratio of their kinetic energies. Which one has a larger kinetic energy?
A more powerful vehiclewould complete a journey in a shorter timethan a less powerful one. We talk of the powerof machines like motorbikes and motorcars.The speed with which these vehicles changeenergy or do work is a basis for theirclassification. Power measures the speed ofwork done, that is, how fast or slow work isdone. Power is defined as the rate of doingwork or the rate of transfer of energy. If anagent does a work W in time t, then power isgiven by
P= work/time
P= W/T. The unit of power is watt.
(i) The rate of doing work is defined as
(a) Energy
(b) Force
(c) Power
(d) None of these
(ii) Total energy consumed divided by total time taken is called as
(a) Average power
(b) Instantaneous power
(c) Both a and b
(d) None of these
(iii) Let A and B having same weight start climbing the rope and reach height of 10m. Let A takes 10sec while B takes 12sec then work done
(a) By both will be same
(b) By A is more than work done by B
(c) By B is more than work done by A
(d) None of these
(iv) Define 1 Watt of power
(v) An electric bulb of 20W is used for 5h per day. Calculate the ‘units’ of energy consumed in one day by the bulb.
Lift an object through a certain height. The object can now do work. It begins to fall when released. This implies that it has acquired some energy. If raised to a greater height it can do more work and hence possesses more energy. From where did it get the energy? In the above situations, the energy gets stored due to the work done on the object. The energy transferred to an object is storedas potential energy if it is not used to cause a change in the velocity or speed of the object.An object increases its energy when raisedthrough a height. This is because work isdone on it against gravity while it is being raised. The energy present in such an objectis the gravitational potential energy.The gravitational potential energy of anobject at a point above the ground is definedas the work done in raising it from the ground by height h
to that point against gravity.Let the work done on the object against gravity beW. That is,
work done, W = force × displacement
= mg × h
Therefore potential energy (PE)= mg*h.
(i) Energy possessed by body due to its position is called
(a) Potential energy
(b) Kinetic energy
(c) Nuclear energy
(d) None of these
(ii) SI unit of potential energy is
(a) Joule(J)
(b) Newton meter(N-m)
(c) both a and b
(d) None of these
(iii)You do work while winding the key of a toy car. The energy transferred to the spring inside is stored as
(a) Potential energy
(b) Kinetic energy
(c) Nuclear energy
(d) None of these
(iv)Find the energy possessed by an object of mass 5kg when it is at a height of 10 m above the ground. Given, g = 9.8 m/s2.
(v)Find the work done by Gravity on an object of mass 5 kg which moves from height 10m to ground when it is released from height of 10 m. Given, g = 9.8 m/s2.
A moving object can do work. An object moving faster can do more work than an identical object moving relatively slow. A moving bullet, blowing wind, a rotating wheel, a speeding stone can do work. How does a bullet pierce the target? How does the wind move the blades of a windmill? Objects in motion possess energy. We call this energy kinetic energy.
Thus, the kinetic energy possessed by an object of mass, m and moving with a uniform velocity, v is
KE = ½ *mv2
The energy possessed by an object is thus measured in terms of its capacity of doing work. The unit of energy is, therefore, the same as that of work, that is, joule (J).
(i) Energy possessed by body which is in motion is called
(a) Potential energy
(b) Kinetic energy
(c) Nuclear energy
(d) None of these
(ii) Which of the following has same unit?
(a) Potential energy and Force
(b) Kinetic energy and work
(c) Both a and b
(d) None of these
(iii) Kinetic energy depends
(a) Inversely on velocity of body
(b) Directly on square of velocity of body
(c) Directly on velocity of body
(d) None of these
(iv) Define kinetic energy of body. Give its SI unit
(v) Is kinetic energy scalar or vector? Justify your answer
Work done by force acting on an object is equal to the magnitude of the force multiplied by the distance moved in the direction of the force. Work has only magnitude and no direction. Work done is negative when the force acts opposite to the direction of displacement. Work done is positive when the force is in the direction of displacement.The unit of work is newton-metre (N m)or joule (J).
(i) Work done is
(a) Scalar quantity
(b) Vector quantity
(c) Tensor quantity
(d) None of these
(ii) When force acts against the direction of displacement then work done will be
(a) positive
(b) negative
(c) both a and b can possible
(d) None of these
(iii) SI unit of work is
(a) Joule(J)
(b) Newton meter(N-m)
(c) both a and b
(d) None of these
(iv)You are lifting stone from floor. Work is done by theforce exerted by you on the stone. Theobject moves upwards. The force youexerted is in the direction ofdisplacement. However, there is theforce of gravity acting on the object. Which one of these forces is doingpositive work?
Which one is doing negative work?
(v) Define 1J of work.
The form of energy can be changed from one form to another. What happens to the totalenergy of a system during or after the process?Whenever energy gets transformed, the totalenergy remains unchanged. This is the law ofconservation of energy. According to this law, energy can only be converted from one form to another it can neither be created nor destroyed. The total energy before and after the transformation remains the same.The lawof conservation of energy is valid inall situations and for all kinds of transformations. Thus during motion the sum of the potential energy and kinetic energy of the object would be the same at all points. That is, potential energy + kinetic energy = constant.Andcalled as mechanical energy.
(i) Which of the energy conversion occur in electric iron?
(a) Electric energy converted into heat energy
(b) Electric energy converted into light energy
(c) Heat energy converted into electrical energy>
(d) None of these
(ii) When ball drops from height which of the energy conversion takes place
(a) Gravitational potential energy converted into kinetic energy
(b) Kinetic energy converted into Gravitational potential energy
(c) Heat energy converted into electrical energy
(d) None of these
(iii) When ball is thrown vertically upward which of the following quantity remains constant?
(a) Energy
(b) Force
(c) Potential energy
(d) None of these
(iv) State law of conservation of energy.
(v) In hydroelectric power plant which energy conversion happens?
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