# Competitive Exams: Physics MCQs (Practice-Test 11 of 35)

• Assertion (A): Fission of235 92 U is brought about by a thermal neutron, whereas that of 238 92U is brought about by a fast neutron.
• Reason (R): 235 92U is an even-odd nucleus, whereas 238 92 U an even-even nucleus
• Assertion (A): A 14-pin package can accommodate only four two-input gates.
• Reason (R): A gate requires only three external pins
1. Vander Waals equation for real gases is p + (a/v2) (v-b) = RT. The dimensional of ‘a’ will be (symbols have their usual meanings)

1. ML5T − 2

2. ML3T − 2

3. ML3T − 1

4. M2LT-2

2. A particle is moving in a circular path with a constant speed v. If q is the angular displacement, then starting from q = 0, the maximum and minimum changes in the momentum will occur when value of q is respectively

1. 450 and 900

2. 900 and 1800

3. 1800 and 3600

4. 900 and 2700

3. The coordinates of a moving particle at time t, are given by x = at2 y = bt2 The speed of the particle is

1. 2 (a + b) t

2. (a2 + b2) ½ t

3. 2 (a2 + b2) ½ t

4. (a + b) t

4. Body 1 of mass M is dropped from a height of 1 m and 1-body 2 of mass 3 m is dropped from a height of 9m. Ratio of time taken by the bodies 1 and 2 to reach the ground is

1. 1: 1

2. 1: 3

3. 3: 1

4. 9: 1

5. The resultant of two forces acting at an angle of 1500 is 10 N and is perpendicular to one of the forces. The other force is

1. 20/3N

2. 10 × 3N

3. 20N

4. 20 × 3 N

6. A body of mass m, moving with velocity u collides elastically with another body at rest having mass M. If the body of mass M moves with velocity then the velocity of the body of mass m after the impact is

1. m-M/m + M u

2. m-M/m + M v

3. m + MV/m + M

4. m-MV/m + M

7. If a body placed at the origin is acted upon by a force F = (i + j + 12 k), then which of the following statements are correct?

1. Magnitude of F is 2 ± 2

2. Magnitude of F is 2

3. F makes an angle of 450 with the Z axis

4. F makes an angle of 30 degree with the Z axis

Select the correct answer using the codes given below:

1. 1 and 3

2. 2 and 3

3. 1 and 4

4. 2 and 4

8. Which one of the following gives the angle made by the resultant velocity after t seconds for a projectile of initial velocity u, projected at an angle q with the horizontal?

1. N/A

2. N/A

3. N/A

4. N/A

9. If the horizontal range of a projectile is equal to the maxi-mum height reached, then the corresponding angle of projection is

1. tan-1 (1)

2. tan-1 (3)

3. tan-1 (4)

4. tan-1 (12)

10. If a person sitting on a rotating stool with his hands out stretched, suddenly lowers his hands, then his

1. kinetic energy win decrease

2. moment of inertia win decrease

3. angular momentum win increase

4. angular velocity will remain constant

11. Match List I with List II and select the correct answer:

 List-I (System) List-II (Expression for moment of inertia) A ring about its axis A uniform circular disc about its axis A solid sphere about any diameter A solid sphere about any tangent MR2/2 ⅖ MR2 7/5 MR2 MR2 9/5 MR2
• A
• B
• C
• D
• 2
• 1
• 3
• 4
• 4
• 3
• 2
• 5
• 1
• 5
• 4
• 3
• 4
• 1
• 2
• 3
12. A cylinder of mass 5 kg and radius 0.1 m is resting on a horizontal platform (parallel to the x-y plane) and is free to rotate about its axis fixed along the y-axis. The platform is given a motion, v in the x direction given by x = = 0.2 cos (10t) m. If there is no slipping, then the maximum torque acting on the cylinder during its motion is

1. 0.2 N-m

2. 2.0 N-m

3. 5.0 N-m

4. 10.0 N-m

13. A stone of mass M tied at the end of a string, is moving in a circle of radius R, with a constant angular velocity w. The work done on the stone, in any half circle, is

1. p MR2 w2

2. 2 MR2 w2

3. MR 2 w2

4. zero