MCQ : Laws Of Motion ( 1 to 1 0 )

LEVEL – I

1. When a body is stationary:

(A) There is no force acting on it

(B) The forces acting on it are not in a contact with it

(C) The combination of forces acting on it balance each other

(D) The body is in vacuum

2. A toy train consists of three identical compartments X, Y and Z. It is pulled by a constant horizontal force F applied on Z horizontally. Assuming there is negligible friction, the ratio of tension in string connecting XY and YZ is:

(A) 2:1

(B) 3:2

(C) 1:2

(D) 2:3

3. Two blocks of masses 2 kg and 1 kg are in contact with each other on a frictionless table, when a horizontal force of 3.0 N is applied to the block of mass 2 kg the value of the force of contact between the two blocks is:

(A) 4 N

(B) 3 N

(C) 2 N

(D) 1 N

4. A block of metal weighing 2 Kg is resting on a frictionless plane. It is struck by a jet releasing water at a rate of 1 Kg/sec and at a speed of 5m/sec. The initial acceleration of the block will be:

(A) 2.5 m/sec2

(B) 5.0 m/sec2

(C) 10 m/sec2

(D) none of above

5. When a force of constant magnitude always act perpendicular to the motion of a particle then:

(A) Velocity is constant

(B) Acceleration is constant

(C) KE is constant

(D) None of these

6. Two masses M1 and M2 are attached to the ends of string which passes over the pulley attached to the top of a double inclined plane. The angles of inclination of the inclined planes are α and β . Take g = 10 ms-2. If M1 = M2 and α = β , what is the acceleration of the system ?

(A) zero

(B) 2.5 ms-2

(C) 5 ms-2

(D) 10 ms-2

7. Starting from rest, a body slides down a 45° inclined plane in twice the time it takes to slide down the same distance in the absence of friction. The coefficient of friction between the body and the inclined plane is:

(A) 0.33

(B) 0.25

(C) 0.75

(D) 0.80

8. A trolley car slides down a smooth inclined plane of angle of inclination θ. If a body is suspended from the roof of the trolley car by an inextensible string of length l, the corresponding tension in the string will be

(A) mg

(B) mg cosθ

(C) mg sinθ

(D) None of these

9. A block of mass m is held at the top of an inclined rough plane of angle of inclination θ . The coefficients of static and kinetic friction are μ1 and μ2 respectively. If the block is pushed down at the verge of slipping, assuming θ < tan-1 μ1 , Its acceleration down the plane is :

(A) g[Sin θ – μ1 Cos θ]

(B) g[Sin θ – μ2 Cos θ]

(C) g( Sin θ – μ1 Cos θ]

(D) g

10. A satellite in force-free space sweeps stationary interplanetary dust at a rate (dM/dt) = αv . The acceleration of satellite is:

(A) -2v2/M

(B) -αv2/M

(C) -αv2/2M

(D) -αv2

ANSWER:

1. (C)   2. (C)   3. (D)   4. (A)   5. (C)   6. (A)   7. (C)   8. (B)   9. (B)   10. (B)  

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