HSSC-I (Class-11) Solved Physics MCQs; Unit-4: Work and Energy (Baluchistan Textbook Board, Quetta) With Verified Answers:



1. When the applied force and covered displacement are parallel to each other than 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 of the following source 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​


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