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.

66.

The working of the beam balance is based on the principle of

A.

moments

B.

conservation of energy

C.

equivalence

D.

floatation

Correct answer is A

The working of the beam balance is based on the principle of moments. The principle of moments states that the sum of the clockwise moments on a beam must be equal to the sum of the counterclockwise moments on the beam. This means that the weight of the object on the left side of the beam must be multiplied by the distance from the fulcrum to the left side of the beam, and the weight of the object on the right side of the beam must be multiplied by the distance from the fulcrum to the right side of the beam. If these two products are equal, then the beam will be in equilibrium.

67.

The branch of physics that deals with the motion of objects and the forces acting on them is called:

A.

Electromagnetism

B.

Thermodynamics

C.

Mechanics

D.

Quantum mechanics

Correct answer is C

Mechanics is the branch of physics that deals with the motion of objects and the forces acting on them. It is the foundation of all other branches of physics, and it is used to study everything from the motion of planets to the motion of electrons.

68.

A charge of \(4.6 × 10^{-5}\)C is placed in an electric field of intensity \(3.2 × 10^4\) \(Vm^{-1}\). What is the force acting on the electron?

A.

1.5 N

B.

3.7 N

C.

4.2 N

D.

2.5 N

Correct answer is A

q=\(4.6 × 10^{-5}\), C=   \(3.2 × 10^4\) \(Vm^{-1}\) F= ?

F=qE

⇒ \(4.6 × 10^{-5}\)C × \(3.2 × 10^4\)

; F= 1.5 N


 

69.

An explosion occurs at an altitude of 312 m above the ground. If the air temperature is -10.00°C, how long does it take the sound to reach the ground?

[velocity of sound at \(0^oC\) = 331 ms-1]

A.

0.94s

B.

0.96s

C.

0.93s

D.

0.95s

Correct answer is B

d=312m.,T =263\(-10^°c\) = -10+273K = 263K, t=?

v= 331√ \(\frac{T}{273}\)

⇒ v = 331×√ \(\frac{263}{273}\)

⇒ v = 324.88 \(ms^-1\)

⇒ v = \(\frac{d}{t}\)

t = \(\frac{d}{t}\) = \(\frac {312}{324.88}\)

t = 0.96s

 

 

70.

The diagram above illustrates the penetrating power of some types of radiation. X, Y and Z are likely

A.

X = α-particle; Y = γ-ray; Z = β-particle

B.

X = α-particle; Y = β-particle; Z = γ-ray

C.

X = γ-ray; Y = α-particle; Z = β-particle

D.

X = β-particle; Y = γ-ray; Z = α-particle

Correct answer is C

The penetrating power of alpha rays, beta rays, and gamma rays varies greatly. Alpha particles can be blocked by a few pieces of paper. Beta particles pass through paper but are stopped by aluminum foil. Gamma rays are the most difficult to stop and require concrete, lead, or other heavy shielding to block them.

Therefore, X = γ-ray; Y = α-particle; Z = β-particle