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#### Laws of Motion Important Questions

11th Standard

Reg.No. :
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Physics

Time : 01:00:00 Hrs
Total Marks : 50
10 x 1 = 10
1. When a car takes a sudden left turn in the curved road, passengers are pushed towards the right due to

(a)

inertia of direction

(b)

inertia of motion

(c)

inertia of rest

(d)

absence of inertia

2. Two masses m1 and m2 are experiencing the same force where m1 < m2.The ration of their acceleration $\frac { { a }_{ 1 } }{ { a }_{ 2 } }$is

(a)

1

(b)

less than 1

(c)

greater than 1

(d)

all the three cases

3. A particle of mass m sliding on the smooth double inclined plane (shown in figure) will experience

(a)

greater acceleration along the path AB

(b)

greater acceleration along the path AC

(c)

same acceleration in both the paths

(d)

no acceleration in both the paths

4. An object of mass m begins to move on the plane inclined at an angle θ. The coefficient of static friction of inclined surface is μs.The maximum static friction experienced by the mass is

(a)

mg

(b)

μs mg

(c)

μs mg sin ፀ

(d)

μs mg cos ፀ

5. Action and reaction

(a)

act on two different objects

(b)

have opposite direction

(c)

have equal magnitude

(d)

all of these

6. Momentum is closely related to

(a)

Force

(b)

Impulse

(c)

Velocity

(d)

K.E

7. A body is moving in a circle with uniform speed v. In moving from a point to another diametrically opposite point.

(a)

The momentum changes by mv

(b)

K.E. changes by 1/2mv2

(c)

The momentum changes by 2mv

(d)

K.E changes by mv2

8. A body of mass 3 kg moves with an acceleration 2ms-2. The change in momentum in one second is

(a)

2/3 kgms-1

(b)

3/2  kgms -1

(c)

6  kgms -1

(d)

1.5  kgms -1

9. A spacecraft of mass M moving with velocity v in free space explodes and breaks into two pieces. After the explosion a mass m of the spacecraft is left stationary. The velocity of  other part is

(a)

$\frac { mv }{ M-n }$

(b)

$\frac { M+n }{ Mv }$

(c)

$\frac { Mv }{ M-m }$

(d)

$\frac { Mv }{ m }$

10. Three blocks of masses 2 kg, 3 kg and 5 kg are connected to each other with light string & then placed on a frictionless surface. The system is pulled by a force F = 10N, then tension T1 is

(a)

1N

(b)

8N

(c)

5N

(d)

10N

11. 5 x 2 = 10
12. Why does a parachute descend slowly?

13. When walking on ice one should take short steps. Why?

14. When a person walks on a surface, the frictional force exerted by the surface on the person is opposite to the direction of motion. True or false?

15. Give examples for inertia frames

16. Give examples for action - reaction forces

17. 5 x 3 = 15
18. What is the meaning by 'pseudo force'?

19. State the empirical laws of static and kinetic friction

20. What is Centripetal force? Write the expression for it?

21. Write the effects of centrifugal force

22. A force of 10 N changes velocity of a body from 20 ms-1 to 40 ms=' in 8 seconds. How much force is required to bring about the same change in 4s.

23. 3 x 5 = 15
24. Explain the motion of blocks connected by a string in
i) Vertical motion
ii) Horizontal motion.

25. Briefly explain 'rolling friction.

26. Briefly explain how is a vehicle able to go round a level curved track. Determine the maximum speed with which the vehicle can negotiate this curved track safely.