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Answer 1

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Answer 2

Required Answers:

1) What is Volume? Find its SI unit?

Ans- This term is used for determining the amount of space occupied by the matter i.e. Solids, liquids and gases. Solids & Liquids have definite volume but Volume of gas is indefinite.

• SI unit of Volume is m³ (Metre ³)

2) When a body is said to be at rest? Give two examples.

Ans- When a body doesn't changes its position with respect to its environment and time, is said to be at rest. Actually, Rest & Motion are relative to each other and it depends upon the observer$.$

Examples:

• A bird sitting on the branch on a tree. If we will observe with respect to the tree, then it is at rest. Reference - Tree

• A passenger sitting infront of us inside the moving bus is in rest with respect to us but is in motion with respect to people outside. Reference - Me

3) Why does the mass remains same everywhere?

Ans- The Mass is the amount of matter contained in a body which will remain constant everywhere because our composition will not change under normal circumstances. Imagine an astronaut who is travelling to space, will have different weight because gravity will differ but mass is same since it's composition will not change.

4) Diffentiate between Incident ray and Reflected Ray.

Ans- When light shows refraction phenomenon on heating any polished reflecting surface,

• The ray that hits the surface is known as Incident Ray.

• And, the ray that bounces back is known as Reflected Ray.

5) What are primary colours? Which colour is made by their blending?

Ans- Primary colours are those colours which can be blend and mixed in different proportions to form all other colours. The three primary colours are:

• Red

• Yellow

• Blue

The colours which are formed by mixing and blending these three primary colours are known as Secondary colours.

6) State the laws of reflection.

Ans- There are two laws of reflection:

• The incident ray, normal and reflected ray lies on the same line.

• The Angle of incidence = Angle of reflection in terms of measure.

7) List any three effects of heat.

Ans- The effects of heating a body are:

• Temperature change: The kinetic energy of the atoms and molecules inside the matter will increases and they start moving at higher speed. The temperature hence rises in most of the cases because of the increase in Average Kinetic energy.

• Expansion of body: The vibration of the particles inside the body will increase and will try to break the force of attraction, they expand from their original shape.

• Change in state: The kinetic energy will increase and force of attraction will decrease which results in the change of phase of matter. From Solid to liquid and liquid to gas.

8) Define heat. Find its SI unit.

Ans- The heat is the form of energy which is transferred from one body to another and gives the sensation of hotness and coldness. These are detected by the Thermoreceptors inside the skin.

• As it is a form of energy, hence the SI unit of heat energy is measured in Joules.

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