Important Multiple Choice Questions of physics || Class 11 ||

1. A particle moves along a straight-line y= 3x + 5. Which coordinate changes at faster rate?

a) X- coordinate 

b) y-coordinate 

c) both x and y 

d) insufficient data

Ans: b) y-coordinate (Let suppose x=1,then y=8 ,x= 2 ,y = 11. So y coordinate is increasing 3 times faster as compare to X- coordinate ) . 

2. If 𝐴⃗ + 𝐵⃗⃗ = 𝐶⃗ and A+B = C then the angle between 𝐴⃗ and 𝐵⃗⃗ is-

a) 0

b) π/4 

c) π/2 

d) π 

Ans: c) π/2

3. If a unit vector is represented by 0.5𝑖− 0.8𝑗+ c k then the value of ‘c’ is-

a) 1 

b) √0.11 

c) √0.01

d) √0.39

Ans: b) √0.11

4. Given that A = B. what is the angle between (𝐴⃗ + 𝐵⃗⃗) and (𝐴⃗ − 𝐵⃗⃗⃗⃗⃗⃗⃗⃗) =?

a) 30°

b) 60°

c) 90°

d) 180°

Ans: d) 180°

5. What is the component of the (3i+4j) along (i + j)?

a) ½ (i + j) 

b) 3/2(i + j) 

c) 5/2 (i + j) 

d) 7/2 (i + j)

Ans: d) 7/2 (i + j)

6. What is the value of (𝐴⃗ + 𝐵⃗⃗).( 𝐴⃗ × 𝐵⃗⃗)?

a) 0 

b) A²-B²

c) A²+B²+2AB 

d) None of these

Ans: a) 0 

7. The angle between (𝐴⃗𝑋𝐵⃗⃗) and (𝐵⃗⃗𝑋𝐴⃗) is-

a) π rad 

b) π/2 rad 

c) π/4 rad 

d) 0

Ans: a) π rad 

8. A man walks 30 m towards north, then 20 m towards east and in the last 30√2m towards south  west. The displacement from origin is –

a) 10 m towards west

b) 10 m towards east

c) 60√2m towards North-west

d) 60√2m towards east north

Ans: a) 10 m towards west

9. A man walks for some time t with velocity (v) due east. Then he walks for the same time t with velocity (v) due north. The average velocity of the man is-

a) 2v 

b) √2v 

c) v 

d) v/√2

Ans: b) √2v

10. If a body covers 3 consecutive equal distances with speeds v1, v2, v3 then the average speed of the body is-

a) 3 𝑣1+𝑣2+𝑣3

b) 2𝑣1𝑣2𝑣 / 1+𝑣2+𝑣3

c) 3𝑣1𝑣2𝑣3𝑣 / 1+𝑣2+𝑣3

d) 3𝑣1𝑣2𝑣3 / 𝑣1 𝑣2+𝑣2 𝑣3+𝑣3 𝑣1

Ans: d) 3𝑣1𝑣2𝑣3 / 𝑣1 𝑣2+𝑣2 𝑣3+𝑣3 𝑣1

11. A particle moves along a straight line such that its displacement at any time t is given by s= (t³- 6t²+3t+4) meters. The velocity when the acceleration is zero is-

a) 3 m/s 

b) -12 m/s 

c) 42 m/s 

d) -9 m/s

Ans: c) 42 m/s

12. The motion of a particle is described by the equation- x = a + b t² where a = 15 cm and b= 3 cm/s2. It's instantaneous velocity at time 3 sec will be-

a) 36 cm/s 

b) 18 cm /s 

c) 16 cm/s 

d) 32 cm/s

Ans: d) 32 cm/s

13. graph between the v2 of a particle and the distance has been showed. The acceleration of particle in Km/h² is- 

a) 2250 

b) 3084 

c) -2250

d) -3084 

Ans: b) 3084

14. Working or rocket or jet is based on-

a) Newton’s, I law

b) Newton’s, II law

c) Newton’s, III law

d) All of three laws

Ans: c) Newton’s, III law

15. A player catches a ball of 200 gm moving with a Speed of 20 m/s. if the time taken to complete the  catch is 0.5 sec, the force exerted on player’s hand is- 

a) 8 N 

b) 4 N 

c) 2 N 

d) 0 

Ans: a) 8 N 

16. find the tension T2 for the system shown in figure-

a) 1g  

b) 2g 

c) 5g  

d) 4g 

Ans: c) 5g

17. The elevator shown in the figure is descending with an acceleration of 2 m/s². The mass of the block A is 0.5 kg. the force exerted by the block A on block B is- 

a) 2 N

b) 4 N 

c) 6 N

d) 8 N

Ans: b) 4 N

18. three blocks are connected as shown in the figure on a horizontal frictionless table. If M1 = 1 kg, M2= 8 kg, M3 = 27 kg and  T3= 36N, T2 will be- 

a) 18 N 

b) 9 N 

c) 3.375 N 

d) 1.75 N

Ans: b) 9 N 

19. The coefficient of friction between two surfaces depends on-

a) The nature of the surface

b) The shape of the surface in contact

c) The area of contact

d) All of the above

Ans: a) The nature of the surface (Smoothness Or roughness of the surface). 

20. A cubical block rests on a plane of µ = 1 √3 . What is the angle of inclination of plane through which  the block just starts to slide-? 

a) 30° 

b) 45° 

c) 60° 

d) 15° 

Ans: a) 30°

21. A force F = (3x2+ 2x- 7) N acts on a 2 kg body because of which the body gets displaced from x= 0 to x = 5cm. the work done by the force will be- 

a) 35 J 

a) 70 J

c) 115 J 

d) 270 J

Ans: a) 70 J

22. A force acts F = (5i+4j) N on a body and produced a displacement d = (6i – 5j+3k) m. the work done will be- 

a) 30 J 

b) 40 J 

c) 10 J 

d) 20 J

Ans: c) 10 J 

23. Two balls of masses 2kg and 4kg are dropped from a height of 60 feet. After a fall of 30 feet each towards the earth, their respective kinetic energies will be in the ratio of- 

a) 1:4 

b) 1;2 

c) 1: √2 

d) √2:1

Ans: a) 1:4

24. Two men weighs in the ratio of 5:3 run up a staircase in times in the ratio 11:9. The ratio of power of first to that of second is- 

a) 15:11 

b) 11:15

c) 11:9 

d) 9:11

Ans: c) 11:9

25. A spring of force constant 800 N/m has an extension of 5 cm. the work done in extending it from 5 cm to 15 cm is- 

a) 16 J 

b) 8 J 

c) 32 J 

d) 24 J

Ans: b) 8 J