Motion
Chapter -2 Motion
SHORT ANSWER TYPE
1. Comment on the statement 'rest and motion are relative terms. Give an example.
Ans- The statement "rest and motion are relative terms" means that whether an object is at rest or in motion depends on the observer. A body at rest with respect to one body , may be at the same in motion with respect to other object.
Example:
Consider a passenger sitting inside a moving train:- The passenger is at rest with respect to train because he is not changing their position relative to the train.
The passenger is in motion with respect to train because the train is moving relative to the ground, and hence the passenger is also moving with it.
2. Fill in the blanks using one of the words: at rest, in motion.
(a) A person walking in a compartment of a stationary train is rest relative to the compartment and is rest relative to the platform
(b) A person sitting in a compartment of a moving train is rest relative to the other person sitting by his side and is motion relative to the platform.
3. Name five different types of motion you know.
Ans:-Types of motion -1. Translatory motion
2. Rotatory motion
3. Circular motion
4. Oscillatory motion
5. Vibratory motion
6. periodic motion
7.Non periodic motion
4. What do you mean by translatory motion ? Give one example.
Ans-A body said to have translatory motion if every point on a moving body moves through the same distance in the same interval of time.
Example- motion of Apple falling vertically down
5. What is rotatory motion? Give two examples.
Ans- When a body moves about to fixed point, the body said to have rotatory motion.
Example-motion of ceiling fan
6. What is meant by circular motion? Give one example.
Ans-If a body moves in a circular path the motion is said to be circular motion.
Example-motion of Satellite around the earth.
7. How does rotatory motion differ from circular motion?
Ans-Rotatory Motion: The axis of rotation is within the object.
Circular Motion: The axis of rotation is outside the object, at the centre of the circular path.
Rotatory Motion: Different points in the object move in concentric circles around the axis.
Circular Motion: The object as a whole moves along a single circular path
8. What is vibratory motion? Give one example.
Ans-The to and fro motion of a part of the body keeping its rest part fixed is called vibratory motion.
Example - Our vocal cords vibrate to produce sound when we speak or sing.
9. What is random motion? Give an example.
Ans- The motion of an object which takes path in no specific direction is called random motion.
Example - Motion of molecules of a gas
10. Name the type/types of motion being performed by each of the following:
(a) Vehicle on a straight road- Rectilinear
(b) Blades of an electric fan in motion - Rotatory
(c) Pendulum of a wall clock- Oscillatory
(d) Smoke particles from chimney-: Random
(e) Hands of a clock- Circular
(f) Earth around the sun - Circular
(g) A spinning top.- Rotatory
11. State the types of motion of the following:
(a) The needle of a sewing machine- periodic
(b) The wheel of a bicycle- Translatory and Rotatory
(c) The drill machine-Translatory and Rotatory
(d) The carpenter's saw- Translatory and Oscillatory .
12. Define the term weight and state its S.I. unit.
Ans- The weight of a body on Earth is the force with which Earth attracts the body. Its SI unit is newton ( N ).
13. How are the units of weight, kgf and newton related ?
Ans- 1 kgf = 9.8 N
14. Which quantity: mass or weight, does not change by change of place?
Ans- Weight changes from place to place.
15. State which of the quantities, mass or weight is always directed vertically downwards.
Ans- Weight is always directed vertically downwards.
C. LONG ANSWER TYPE QUESTIONS
1. Explain the meaning of the terms rest and motion.
Ans-A body said to be at rest ,if he does not change its position with respect to its immediate surroundings.
A body said to be in motion, if it changes its position with respect to its immediate surroundings.
2. Explain the meanings of (i) rectilinear motion, and (ii) curvilinear motion. Give one example of each.
Ans- Rectilinear motion - the motion of a body in a straight line is called linear motion.
Example - A ball is dropped, falling vertically down.
Curvilinear motion - the motion of a body in a curved path is called curvilinear motion.
Example - The motion of a cycle while taking a turn on the road
3. Explain oscillatory motion by giving one example.
Ans- The to and fro motion of a body from its rest position is called the oscillatory motion for example the motion of the pendulum of a wall clock.
4. Differentiate between periodic and non-periodic motions by giving an example of each.
Ans-Periodic motion- A motion which gets repeated after regular interval of time is called Periodic motion, for example the earth complete one revolution about the earth in 365 1/4 days and this motion is repeated after every 365 1/4 days.
Non periodic motion - The motion which does not repeat itself after a regular interval of time is called non periodic motion, example -A footballer running on a field.
5. Give two examples to illustrate that a body can have two or more types of motion simultaneously
.Ans- 1. A car Wheel:
- Rotational Motion: The wheel rotates around its own axis as it rolls.
- Translational Motion: Simultaneously, the wheel moves forward along a surface.
- 2. Earth around the Sun:
- Rotational Motion: The Earth spins around its axis, resulting in day and night.
- Circular Motion: The Earth simultaneously moves around the Sun,
6. Distinguish between uniform and non-uniform motion, giving an example of each.
Ans-
| Example |
| Car moving at a constant speed on a highway. Non uniform motion - |
| Car again moving after halt of 5 minutes. |
7. How do you determine the average speed of a body in non-uniform motion ?
Average speed= Total distance÷ total time taken
8. State three differences between mass and weight.
| Feature. | Mass | Weight |
|---|
| Definition | Amount of matter in an object | Force due to gravity acting on an object |
| Device | Beam balance | Spring balance |
| Units | kilogram (kg) | newton (N) |
Activity - Simple Pendulum
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