11th Physics MCQs Preparation 2022 and Onwards (Unit: Work and Energy: Set-1 (29 MCQs)) for National MDCAT, ECAT, FPSC, PPSC, JOB Exam, Physics Lecturer, SSC, HSSC (F.Sc.), BS, MS Exams NTS, ETS ETc..



1. When the applied force and covered displacement are parallel to each other then work done by the body is;




... Answer is C. Maximum
W = F.d = Fd cos θ So when F and D are parallel i.e. θ = 0° and Cos 0° = 1. So maximum work


2. A man pulling a bag with the force of 15 N at an angle of 60° with the horizontal plane. If the bag covers a distance of 10 m, then the work done by the man is




... Answer is B. 75 J
W = F.d = Fd cos θ


3. The area under a curved in a force and displacement graph shows that?




... Answer is B. Work under a variable force
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4. If the velocity is doubled then the K.E of the body will be:




... Answer is D. Four times
K.E = 1/2 m v²


5.  A bullet of mass 20 g is fired with a velocity of 2000 m s⁻¹, the KE of the bullet is;




... Answer is D. 40000 J
K.E = 1/2 m v²


6. A body of mass 100 g is raised vertically from the surface of the earth in a gravitational field. The P.E of the body at a height of 100 m is:




... Answer is C. 98 J
P.E = mgh


7. What is the power of an electric motor when it consumes energy of 9 ｘ 10³ J in 3 s? :




... Answer is D. 4 hp
1 hp = 746 watt


8. Absolute potential energy of a body at the surface of the earth is




... Answer is C. `\frac {GmM}{R}`
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9. What is the value of the potential energy of a body at the height where the value of 'g' is zero.




... Answer is A. Zero
P.E. = mgh when g=0 then P.E = 0


10. When the velocity of the body of mass 10 kg is increased from 2 m s⁻¹ to 8 m s⁻¹ then the work done of the body is




... Answer is C. 300 J
K.E = W = 1/2 m v²


11. Which force is a non-conservative?




... Answer is B. Friction force
Non-conservative forces have dissipative effects


12. Which one of the following sources of energy is not a fossil fuel?




... Answer is B. Uranium
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13. Conventional method of energy extraction is




... Answer is D. Biomass power
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14.  One-megawatt hour is equal to:




... Answer is C. 3.6 ｘ 10⁹ J
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15. If the speed of an object is tripled, its kinetic energy is increased by




... Answer is D. 9 times
K.E = 1/2 m v²​


16. You push a heavy crate down a ramp at a constant velocity. Only four forces act on the crate. Which force does the greatest magnitude of work on the crate?




... Answer is A. The force of friction
 On Horizontal Surface only pushing force is responsible for sliding the object and that is greater that the friction. But on the ramp, the combined gravitational force and pushing force are responsible for sliding the crate down. The normal force does not work. So Friction force is more among all the forces.


17. The force constant of a wire is k and that of the other wire is 3k when both the wires are stretched through the same distance, if the work done is W₁ and W₂, then




... Answer is D. W₂ = 3 W₁
Force Constant of one wire let k₁ = k and another wire k₂ = 3k = 3k₁ 👉 Work required = change in energy 👉 W = 𝛥 E = 1/2 kx² 👉 W₁ = 𝛥 E₁ = 1/2 kx² 👉 W₂ = 𝛥 E₂ = 1/2 (3k) x² = 3 (1/2 k x²) = 3 W₁


18. Escape velocity on the surface of the earth is 11.2 km s⁻¹. If the mass of the earth increases to twice its value and the radius of the earth becomes half the escape velocity is




... Answer is C. 22.4 km s⁻¹
Ve = √ (2GMe/Re)= 11.2 km s⁻¹ 👉 When Me with 2 Me and Re with 1/2 Re we get 👉 Ve = √ 4 (2GMe/Re)= 2 √ (2GMe/Re) = 2 (11.2 km s⁻¹) = 22.4 km s⁻¹ 👉 i.e.. The Escape velocity becomes double


19. An example of non-conservative force is:




... Answer is C. Frictional force
The Frictional Force is non-conservative because if an object is moved over a rough surface between two points along different paths. The work done against the frictional force certainly depends on the path followed. Electric and gravitational forces are conservative and magnetic may and may not be conservative depending on some conditions.


20. When the speed of your car is doubled, by what factor does its kinetic energy increase?




... Answer is C. 4
K.E = 1/2 m v² 👉 by replacing v with 2v 👉 K.E = 1/2 m (2v)² = 4 (1/2 m v²) = 4 K.E


21. One horsepower is given by:




... Answer is A. 746 W
In British Engineering System the unit of Power is called Horse Power (hp) and numerically, 1 hp = 746 W (watts)


22. Work is said to be negative when F and d are: :




... Answer is B. Anti Parallel
F and d antiparallel means the angle between them is 180°. Work W is sculler quantity is equal to the dot product of F and d. 👉 W = F • d = F d cos𝜃 = F d cos (180°) = -Fd (negative work)


23. Two bodies of masses m₁ and m₂ have equal momentum their kinetic energies E₁ and E₂ are in the ratio




... Answer is C. m₂ : m₁
 Given: P1 = P2 (given) 👉 K.E = E = 1/2 mv² = m² v² / 2 m = p² /2m 👉 E₁/E₂ = (p₁² /2m₁) / (p₂² /2m₂) 👉 E₁/E₂ = m₂/m₁ E₁ : E₂ = m₂ : m₁


24. The atmosphere is held to the earth by




... Answer is B. Gravity
The atmosphere (gasses) is held to the earth by the earth's gravitational force.


25. If momentum is increased by 20% then K.E increases by




... Answer is A. 44%
K.E = E = 1/2 mv² = m² v² / 2 m = p² /2m 👉 K.E = p² /2m 👉 increase of 20% 👉 Δ K.E = (p + 20% P )² /2m 👉 Δ K.E = (p + (20/100) P )² /2m 👉 Δ K.E = {p² + (400/10000) p² + 40/100 P²)} /2m 👉 by taking p² common Δ K.E =  { 1 + 0.04 + 0.4 )} p²/2m 👉 Δ K.E = 1.44 K.E 👉 Δ K.E - K.E = 1.44 K.E - K.E = .44 K.E = 44 % K.E


26. If the K.E of a body becomes four times the initial value, then new momentum will




... Answer is A. Become twice its initial value
👉 K.E = p² /2m 👉 P = √ (2m K.E) 👉 by increasing K.E four-time than P' = √ (2m 4 K.E) 👉 P' = 2 √ (2m K.E) = 2 P


27. Two bodies with kinetic energies in the ratio of 4 : 1 are moving with equal linear momentum. The ratio of their masses is :




... Answer is D. 1 : 4
K.E₁ : K.E₂ = 4 : 1 (given) 👉 K.E = E = 1/2 mv² = m² v² / 2 m = p² /2m 👉 K.E₁/K.E₂ = (p₁² /2m₁) / (p₂² /2m₂) 👉 4/1 = m₂/m₁ 👉 by reversing the friction we get m₁/m₂ = 1/4 👉 m₁ : m₂ = 1 : 4


28. A body of mass 5 kg is moving with a momentum of 10 kg m s⁻¹. A force of 0.2 N acts on it in the direction of motion of the body for 10s. The increase in its kinetic energy is




... Answer is D. 36.7
K.E (initial) = p² /2m = (10 kg m s⁻¹)²/2 x 5 kg = 10 J 👉 Now K.E (final) = 1/2 m vf² when a F= 0.2 N at t= 10 s 👉 we have find vf = ? using equation vf = vi + at 👉 from P= mvi 👉 vi =p/m = 10 / 5 = 2 m/s 👉 a = F/m = 0.2/5 = 0.4 m/s² 👉 Now vf = vi + at = 2 m/s + 0.4 m/s² x 10 s = 2.4 m/s 👉 And K.E (final) = 1/2 m vf²​ = 0.5 x g kg x 2.4 m/s = 14.4 J 👉 increase in K.E = K.E (final) - K.E (initial) = 14.4 J - 10 J = 4.4 J ----Ans


29.  If force and displacement of a particle in the direction of force are doubled. Work would be




... Answer is B. 4 times
W = Fd 👉 if we replace F with 2F and d with 2d then 👉 W' = 2F x 2d = 4 Fd = 4 F



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Or 

Select from the below Links for HSSC-I (Class-11) :  Physics MCQS Preparation


1. Unit:  Measurements: Set-1 (32 MCQs), Set-2 (50 MCQs), Set-3 (50 MCQs),                                   Set-4 (50 MCQs),   Set-5 (50 MCQs),  

2. Unit:  Vectors and Equilibrium: Set-1 (34 MCQs), 

3. Unit:  Force and Motion: Set-1 (34 MCQs), 

4. Unit:  Work and Energy: Set-1 (29 MCQs), 

5. Unit:  Rotational and Circular Motion: Set-1 (31 MCQs), 

6. Unit:  Fluid Mechanics or Dynamics: Set-1 (31 MCQs), 

7. Unit:  Oscillations : Set-1 (27 MCQs), 

8. Unit:  Waves : Set-1 (27 MCQs), 

9. Unit:  Physical Optics : Set-1 (27 MCQs), 

10. Unit:  Thermodynamics: Set-1 (34 MCQs),  

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