Question Detail

If no external force acts on a system of bodies, the total linear momentum of the system of bodies remains constant. Which law states this ?

Newton first law
Newton second law
Newton third law
Principle of conservation of linear momentum

Answer: Option D

1. Which law states, "The rate of loss of heat by a body is directly proportional to the difference in temperature between the body and the surroundings."

Doppler's Effect
Newton's law of cooling
Kirchhoff's Law
Stefan's Law

Answer: Option B

Explanation:

Doppler's Effect - The Doppler effect can be described as the effect produced by a moving source of waves in which there is an apparent upward shift in frequency for observers towards whom the source is approaching and an apparent downward shift in frequency for observers from whom the source is receding.

Kirchhoff's Law - Kirchhoff's Law signifies that good absorbers are good emitters.

Stefan's Law - The radiant energy emitted by a black body per unit area per unit time is directly proportional to the fourth power of its absolute temperature.

2. Which instrument is used to measure changes in volume of substances ?

Dyanamo
Dilatometer
Cyclotron
Electroscope

Answer: Option B

Explanation:

Dyanamo - is used to convert mechanical energy into electrical energy,

Cyclotron - is a charged particle accelerator which can accelerate charged particles to high energies,

Electroscope - is used to detect the presence of an electric charge.

3. What is the maximum value of deforming force upto which a material shows elastic property and above which the material loses it ?

Elasticity
Strain
Elastic Limit
Stress

Answer: Option C

4. What is newton third law of motion ?

Every body maintains its initial state rest or motion unless no external force is applied.
The rate of change in momentum of a body is directly proportional to the applied force on the body and takes place in the direction of force.
To every action there is equal and opposite reaction.
None of above.

Answer: Option C

Explanation:

Newton First Law of Motion : Every body maintains its initial state rest or motion unless no external force is applied.

Newton Second Law of Motion : The rate of change in momentum of a body is directly proportional to the applied force on the body and takes place in the direction of force.