# UPSC MCQs Quiz 17: Science (Physics) with answers

1. One astronomical unit is the average distance between

1. Earth and the Moon
2. Earth and the Sun
3. Jupiter and the Sun
4. Pluto and the Sun

2. The displacement of a particle at time is given by  x =aj + bj+-t2k 2 where a, b and c are positive constants. Then the particle is

1. accelerated along k-direction
2. decelerated along k-direction
3. decelerated along j-direction
4. accelerated along j-direction

3. A car is moving with a uniform speed. However, its momentum is changing. Then the car

1. may be on an elliptical path
2. is moving on a straight path without acceleration
3. is moving on a straight path with acceleration
4. is moving without any acceleration

4. A spherical body moves with uniform angular velocity (ro) around a circular path of radius r, which one of the following statement is correct ?

1. The body has no acceleration
2. The body has a radial acceleration co2r directed towards centre of path
3. The body has a radial acceleration
4. The body has an acceleration os2 tangential to its path.

5. If d denotes the .distance covered by a car in time t and S denotes the displacement by the car during the same time, then

1. d < | S |
2. d = | S |
3. d > | S |
4. d < | S |

6. A force F is applied on a body (which moves on a straight line) for a duration of 3 s. The momentum of the body changes from 10 g cm/s to 40 g cm/s. The magnitude of the force F is

1. 10 dynes
2. 10 newtons
3. 120 dynes
4. 12 dynes

7. To avoid slipping while walking on ice, one should take smaller steps because of the

1. friction of ice is large
2. larger normal reaction
3. friction of ice is small
4. smaller normal reaction

8. If the radius of the earth was shrink by one per cent, mass remaining the same, the value of g on the earth’s surface would

1. increase by 0.5%
2. increase by 2%
3. decrease by 0.5%
4. decrease by 2%

9. If the earth was stop rotating, the value of g

1. increases
2. decreases
3. remain unchanged
4. becomes zero

10. A ‘rectifier’ is an electronic device used to convert

1. AC voltage into DC voltage
2. DC voltage into AC voltage
3. sinusoidal pulse into square pulse
4. None of the above

• 1. (b)
• 2. (a)
• 3. (a)
• 4. (b)
• 5. (c)
• 6. (a)
• 7. (c)
• 8. (d)
• 9. (a)
• 10. (a)