# Top Physics Questions and Answers

- A body is thrown vertically upward from the ground. It reaches a maximum height of 20 min 5 sec. After what time, it will reach the ground from its maximum height position?

(a) 2.5 sec (b) 5 sec (c) 10 sec (d) 25 sec

Answer: B.

2. What is the practical unit of loudness?

Answer: Decibel (dB).

3. Among the following, the unit of sound absorption is _

Answer: Sabin.

4. What are the elements required for the sensation of hearing?

Answer: A vibrating source, a propagating medium, and a receiver namely ear.

5. If a car at rest accelerates uniformly to a speed of 144 km/h in 20 s, it covers a distance of

(a) 2880 m (b) 1440 m (c) 400 m (d) 20 m

Answer: C.

6. What is supersonic?

Answer: Supersonic refers to the speed of an object moving with a speed greater than that of sound.

7. 2 December 1942 is known for:

Answer: The creation of the first controlled chain reaction.

8. What are the essential characteristics of a musical sound?

Answer: Loudness, pitch, and quality are the characteristics of a musical sound.

9. A car moving with a speed of 40 km/h can be stopped by applying brakes at least after 2 m. If the same car is moving with a speed of 80 km/h, what is the minimum stopping distance?

(a) 8 m (b) 6 m (c) 4 m (d) 2 m

Answer: A.

10. What is known as the study of sound?

Answer: Acoustics.

11. The Standard Unit of measurement of magnetic field strength is _

Answer: Ampère per meter.

12. What is the distance between a compression and its nearest rarefaction in a longitudinal wave?

Answer: L/2.

13. Two bodies, A (of mass 1 kg) and B (of mass 3 kg), are dropped from heights of 16m and 25m, respectively. The ratio of the time taken by them to reach the ground is

(a) 12/5 (b) 5/12 (c) 4/5 (d) 5/4

Answer: C.

14. How will you show by experiment that there is a transfer of energy by the wave?

Answer: We place a cork on water and then throw a stone on water near the cork.

15. An engine develops 10 kW of power. How much time will it take to lift a mass of 200 kg to a height of 40 meters (g = 10 ms2)

Answer: 8 sec.

16. Why is sound heard more intense in carbon dioxide in comparison to air?

Answer: The intensity of sound increases with increase in the density of the medium.

17. A man of 50 kg mass is standing in a gravity-free space at a height of 10 m above the floor. He throws a stone of 0.5 kg mass downwards with a speed 2 m/s. When the stone reaches the floor, the distance of the man above the floor will be:

(a) 9.9 m (b) 10.1 m (c) 10 m (d) 20 m

Answer: B.

18. A wave is expressed by the equation, Y=0.5 sin 71 (0.01 x-3t), where y and x are in meter and t in seconds. Find the speed of propagation?

Answer: V – 300 m/sec.

19. What is called the energy, which an electron acquires when accelerated through a potential difference of 1 volt?

Answer: 1 e v.

20. Which property of sound is affected by a change in air temperature?

Answer: Wavelength.

21. A bus is moving on a straight road towards the north with a uniform speed of 50 km/hour turns through 90°. If the speed remains unchanged after turning, the increase in the velocity of the bus in the turning process is

(a) 70.7 km/hour along south-west direction (b) zero (c) 50 km/hour along west (d) 70.7 km/hour along north-west direction.

Answer: A.

22. Which property of a wave is independent of the other?

Answer: Amplitude.

23. What is called the perpendicular distance from the effort to fulcrum?

Answer: Effort arm.

24. Where can transverse waves propagate?

Answer: Not in a gas but in a metal.

25 When milk is churned, the cream gets separated due to

(a) centripetal force (b) centrifugal force (c) frictional force (d) gravitational force

Answer: B.