# Motion in One Dimension Exe-2A Very Short Answer Physics Class-9 ICSE Selina Publishers

Motion in One Dimension Exe-2A Some Terms Related to Motion Very Short Answer Type for Class-9 ICSE Concise Physics. There is the solutions of Very short Answer type Questions of your latest textbook which is applicable in 2023-24 academic sessionVisit official Website CISCE for detail information about ICSE Board Class-9.

## Motion in One Dimension Exe-2 A Some Terms Related to Motion Very Short Answer

(ICSE Class – 9 Physics Concise Selina Publishers)

 Board ICSE Class 9 Subject Physics Writer / Publication Concise selina Publishers Chapter-2 Motion in One Dimension Exe – 2 A Some Terms Related to Motion Topics Solution of Exe-2(A) Very Short Answer Type Academic Session 2023-2024

### Exe-2A Some Terms Related to Motion Very Short Answer Type

Ch-2 Motion in One Dimension Physics Class-9 ICSE Concise

Page 38

#### Question 1. State whether the following quantity is a scalar or vector?

 (a) pressure (d) force (b) momentum (e) energy (c) weight (f) speed

(a) Pressure is a scalar quantity.

(b) Momentum is a vector quantity.

(c) Weight is a vector quantity.

(d) Force is a vector quantity.

(e) Energy is a scalar quantity.

(f) Speed is a scalar quantity.

#### Question 2. Write the parameters required to express a scalar quantity.

Answer : Two parameters are required to express a scalar quantity :

1. Unit in which the quantity is being expressed.

2. Numerical value of the measured quantity.

#### Question 3. Name the parameters required to express a vector quantity.

Answer : Parameters are required to express a vector quantity :

1. Unit in which the quantity is being expressed.

2. Numerical value of the measured quantity.

3. Direction.

#### Question 4. What does the negative sign with a vector quantity indicates?

Answer : The negative sign with a vector quantity implies the reverse (or opposite) direction. e.g., the forces and are in opposite directions.

#### Question 5. When is a body said to be at rest?

Answer : A body is said to be at rest if it does not change its position with respect to its immediate surroundings.

#### Question 6. When is a body said to be in motion?

Answer : A body is said to be in motion if it changes its position with respect to its immediate surroundings.

#### Question 7. What do you mean by motion in one direction?

Answer : When a body moves along a straight line path, its motion is said to be one-dimensional motion.

(Motion in One Dimension Exe-2A Very Short Class-9 ICSE)

#### Question 8. Define displacement. State its unit.

Answer : The shortest distance from the initial to the final position of the body is called the magnitude of displacement. It is in the direction from the initial position to the final position.

Its SI unit is metre (m)

#### Question 9. When is the magnitude of displacement equal to the distance?

Answer  : The magnitude of displacement is equal to distance if the motion of the body is one-dimensional.

#### Question 10. Define velocity. State its unit.

Answer : The velocity of a body is the distance traveled per second by the body in a specified direction.

Its SI unit is metre/second (m/s).

#### Question 11. Define speed. What is its S.I. unit?

Answer : The speed of a body is the rate of change of distance with time.

Its SI unit is metre/second (m/s).

#### Question 12. Which quantity-speed or velocity-gives the direction of motion of a body?

Answer : Velocity gives the direction of motion of the body.

#### Question 13. When is instantaneous speed the same as the average speed?

Answer : Instantaneous velocity is equal to average velocity if the body is in uniform motion

#### Question 14. Define acceleration. State its unit.

Answer : Acceleration is the rate of change of velocity with time.

Its SI unit is metre/second2 (m/s2).

#### Question 15. What is meant by the term retardation? Name its S.I. unit.

Answer : Retardation is the decrease in velocity per second.

Its SI unit is metre/second2 (m/s2).

#### Question 16. Which of the quantity-velocity or acceleration-determines the direction of motion?

Answer : Velocity determines the direction of motion.

#### Question 17. Define the term acceleration due to gravity. State its average value.

Answer : When a body falls freely under gravity, the acceleration produced in the body due to the Earth’s gravitational acceleration is called the acceleration due to gravity (g). The average value of g is 9.8 m/s2.

—  : End of Motion in One Dimension Exe-2A Some Terms Related to Motion Very Short Answer Type  Solutions :–

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