Loading [MathJax]/jax/output/HTML-CSS/jax.js
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.

736.

A block and tackle pulley arrangement has 6 pulleys in which an effort of 50N supports a load of 200N, calculate the efficiency of the machine

A.

80.0%

B.

76.6%

C.

66.7%

D.

60.7%

Correct answer is C

Efficiency = maV.R x 1001

V.R = number of pulleys = 6

ma = LoadEffort = 20050 = 4

Efficiency = 46 × 100 = 66.67%

737.

A cell of internal resistance 2 π supplies current to a 6 π resistor. The efficiency of the cell is

A.

12.0%

B.

25.0%

C.

33.3%

D.

75.0%

Correct answer is C

Internal resistance determine the maximum current that can be supplied

Efficiency = rR × 100

= 26 × 100

= 33.3%

738.

Calculate the specific latent heat of vaporization of steam of 1.13 x 106J of heat energy is required to convert 15kg of steam to water.

A.

7.53 x 105 Jkg1

B.

7.53 x 10-2Jkg1

C.

7.53×104Jkg1

D.

7.53 x 10-3Jkg1

Correct answer is C

Quantity of heat = mass(m) × specific latent heat (L)
Q = mL
L = Qm

= 1.13×10615

= 7.53×104Jkg1

739.

Under which of the following conditions is workdone

A.

A man supports a heavy food above his head with his hands

B.

A boy climbs onto a table

C.

A man pushes unto a table

D.

A woman holds a pot of water

Correct answer is B

 

For work to be done, distance must be involved because
workdone = force × distance

740.

Under what conditions are cathode rays produced in a discharge tube?

A.

High pressure and low voltage

B.

High pressure and high voltage

C.

Low pressure and low voltage

D.

Low pressure and high volatge

Correct answer is D

 

Cathode rays are produced in a discharge tube under Low pressure and high voltage