HSSC-I (Class-11) Solved Physics MCQs; Unit-3: Force and Motion (Baluchistan Textbook Board, Quetta) With Verified Answers:



1. What is the displacement of the moving body in the following figure.





... Answer is B. 7m
The shortest distance is called displacement. 4m + 3m = 7m


2. Acceleration due to the uniform velocity of a body is




... Answer is D. Zero
If a body is moving with uniform velocity, the acceleration will be zero in the direction of motion.


3. Third equation of motion is independent of:




... Answer is A. Time
2aS= vf² - vi²


4. What is the speed of the cyclist between S₁ and S₂ as shown in the figure.






... Answer is C. 30 km h⁻¹
S = 80-20 = 60 m and t = 4 hrs - 2 hrs = 2, so, v = `\frac {s}{t}` = v = `\frac {60 m}{2 h}` = 30 km h⁻¹


5.  What will be the velocity of a body when it starts its motion from rest and after 5s its acceleration becomes 2 m s⁻¹




... Answer is B. 10 m s⁻¹
vi = 0 m s⁻¹, a = 2 m s⁻¹, t = 5s, Now using 1st equation of motion vf = vi + at = 0 + 2 x 5 = 10 m s⁻¹


6. What is the velocity of an object when it reaches point P to point Q in 2s along a semicircle radius of 2m?





... Answer is C. 2 m s⁻¹
Velocity = displacement / time `\vec v` = `\frac {vec v}{t}` Here displacemennt is two radius ie 2 x 2m = 4m and t= 2s so, `\vec v` = `\frac {4m}{2s}`= 2 m s⁻¹



7. The Sl unit of weight is :




... Answer is D. Newton
Weight is force


8. What is the acceleration produced by a force of 0.5 N applied on a body of mass 0.1 kg?




... Answer is D. 5 m s⁻²
F= ma or a = `\frac {F}{m}` = `\frac {0.5 N}{0.1 kg}` = 5 m s⁻²


9. Three masses that are connected by a massless spring are shown in the figure. What will be the value of F₂?






... Answer is C. 24 N
⇒ F₁ = 5a kg -----------(1) where a is the acceleration ⇒ F₂ - F₁ = 3a kg --------(2) ⇒ 30 N - F₂ = 2a kg --------(3) ⇒ by adding (1) and (2) we get F₂ = 8a kg ------------(4) ⇒ by adding (3) and (4) we get 30 N = 10 a kg or a = 3 m s⁻² ⇒ putting the value of an equation (4) F₂ = 8 (3 m s⁻²) kg = 24 N


10. Rate of change of momentum is




... Answer is B. Force`
 F = ma = m `\frac{v}{t}` =`\frac{mv}{t}` = `\frac{ΔP}{Δt}`


11. A body moves from point P to Q with a speed of 6 m s⁻¹ along a straight line then from Q to P with a speed of 4 m s⁻¹. What is the average speed over the entire trip?




... Answer is C. 5 m s⁻¹
Average Speed = `\frac {v_1 + v_2}{2}`


12. What is the value of impulse in the force-time curve as shown in the figure.





... Answer is B. 1350 N s
Impulse = ΔF x Δt


13. Impulse always changed




... Answer is B. Momentum
Impulse-Momentum Theorem


14.  In a one-dimensional elastic collision of two bodies of the same masses, what will happen if the moving body collides with the mass which is initially at rest?




... Answer is D. Moving body will come to rest and the mass at rest will start motion.
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15. In projectile motion, the horizontal component of acceleration of a body is:




... Answer is A. Zero
As the horizontal component of the velocity remain constant in projectile motion, so ax = 0


16.. At what angle does a projectile gain its maximum height:




... Answer is D. 90°
Formula for Height of Projectile H = `\frac {(v_0 sinፀ)^2 }{2g}` so, if ፀ = 90° and Sine 90° =1 so maximum height


17. A rocket works on basis of :




... Answer is C. Newton's 3rd law
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18. The vertical and horizontal distances of the projectile will be equal if the angle of projection is:




... Answer is D. 76°
Compare the equation of Range and height of the projectile and we will get 0 = tan⁻¹ (4) = 76°


19. The quantitative measure of the inertia of a body is:




... Answer is A. Mass
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