Physics questions and answers

Physics Questions and Answers

If you want to learn more about the nature and properties of matter and energy or you're simply preparing for a Physics exam, these Physics past questions and answers are ideal for you.

441.

An object is acted upon by a system of parallel forces causing the object to be in state equilibrium. Which of the following statement is not correct

A.

the resultant of the parallel forces is zero

B.

the algebraic sum of all the moments of the forces is zero

C.

all the parallel forces must not be equal in magnitude and direction

D.

the sum of forces in one direction must be equal to the sum of forces in the opposite direction

Correct answer is C

all the parallel forces must be equal in magnitude and direction

443.

A rectangular solid block has length 10cm, breadth 5cm and height 2cm. If it lies on a horizontal surface, and has density 100kg/m\(^3\), calculate the pressure it exerts on the surface.

A.

20 N/m\(^2\)

B.

100 N/m\(^2\)

C.

400 N/m\(^2\)

D.

300 N/m\(^2\)

Correct answer is A

P = F
A
= mg
A
= (ρ × v) × g
A
= ρ × (A × h) × g
A


P = 100 × 2 × 10\(^{-2}\) × 10 = 20 N/m\(^2\)

444.

Which of the following statements are correct of the production and propagation of waves?
I. vibration produces waves
II. waves transmit energy along the medium
III. the medium through which the wave travels does not travel with the wave
IV. waves do not require any medium for transmission

A.

I & IV only

B.

II & IV only

C.

III & IV only

D.

I, II and III only

Correct answer is D

- Waves are produced by vibration
- Waves transmit energy along the medium
- Particles of a medium vibrate with the wave motion without the entire medium
- Some waves require medium for transmission (mechanical).

445.

The mass of water vapour in a given volume of air is 0.05g at 20°C, while the mass of water vapour required to saturate it at the same temperature is 0.15g. Calculate the relative humidity of the air.

A.

3.33%

B.

5.55%

C.

33.33%

D.

55.55%

Correct answer is C

RH = mass of water vapour in volume of air
mass of water vapour for saturation

 

RH = m
M
= 0.05
0.15
× 100 = 5
0.15
= 500
15
= 33.33%