Ch-02: Kinematics

Ch-02: Kinematics
This post contains the Physics Chapter 2 Short Qs for Class 9. Name of the 2nd chapter is Kinematics and all the short Qs are solved. Students of 9th Class can prepare these short Qs for the exams. However, they should prepare other Qs as per the instructions of their teachers too.
Q.1: A car travelling at 10 mS-1 accelerates uniformly at 2mS-2. Calculate its velocity after 5 seconds.
Solution. Vi = 10 mS-1 a = 2 ms-2 t = 5s Vf = ? Using the equation: Vf = Vi + at Vf = Vi + at Vf = 10 mS-1 + 2 ms-2 x 5s The velocity of the car after 5s is 20 mS-1
Q No.2 What would be the shape of a speed-time graph of a body moving with variable speed?
Ans. The shape of the velocity-time graph in zigzag when the body was variable speed.
Q No.3. Define Random motion.
Ans. The disordered or irregular motion of an object is called random motion.
Q No.4. Define rotatory motion and give an example.
Ans. The spinning motion of a body about its axis is called its rotatory motion.
Q No.5 Differentiate between speed and velocity.
Ans. Speed: The distance covered by an object in unit time is called its speed.

Velocity: A body has uniform speed if it covers equal distances in equal distances in equal intervals of time however short the interval may be.

Q No.6 Define vector and write the name of two vector quantities.

Ans. A vector quantity is described completely by its magnitude and direction.

Vector quantities:

1. Displacement, velocity
2. Acceleration, force

Q No.7: How can vectorquantities be represented graphically.

Ans. Graphically, A vector quantity is represented by a straight line, with arrow-head at it one end. The length of its straight line represents the magnitude and arrow-head shows the direction of the vector.

Q No.8: Differentiate between linear and random motion. Ans. Linear motion: Straight line motion of a body is known as its linear motion.

Random motion: The disordered or irregular motion of an object is called random motion.

Q No.9: Can a body moving at a constant speed have acceleration?

Ans. Yes, it is possible. The uniform circular motion is an example of a body which moves with constant speed.

Q No.10: Differentiate between scalar and vector. Ans. A scalar quantity is described completely by its magnitude only.

Vector: A vector quantity is described completely by magnitude and direction.

Q No.11: What would be the shape of the speed-time graph of moving with variable speed?

Ans. The shape of the velocity-time graph is zigzag when the body has variable speed.

Q No.12: Define acceleration.

Ans. Acceleration is defined as the rate of change of velocity of a body.

Q No.13: What is meant by positive acceleration and negative acceleration.

Positive acceleration: Acceleration of a body is positive if its velocity increases with time, is called positive acceleration. Negative acceleration: Acceleration of a body is negative if the velocity of the body decreases with time is called negative acceleration.

Q No.14: What is meant by Kinematics?

Ans. Kinematics is the study of the motion of an object without discussing the cause of motion.

Q No.15: Write the difference between circular and vibratory motion. Ans. Circular motion: The motion of an object in a circular path is known as circular motion.

Vibratory motion: To and fro motion of a body about its mean position is known as vibratory motion.

Q No.16: Define rest and motion.

Ans. If a body is changing its position according to its surroundings is said to be in motion and if a body is not changing its position with respect to its surrounding is said to be in rest.