## Physics IX Notes Chapter 2 KINEMATICS

**what is kinematics? Also, define rest and motion?**

Ans. ** Kinematics:-**the branch of physics which deals with the study of the motion of bodies without reference to force is called kinematics.

** Rest:-**if a body does not change its position with respect to its surrounding then the body is called in a state of rest. For example, a boy is setting in his chair in his classroom .then he does not change his position with respect to his surrounding and we say that boy is in a state of rest.

** Motion:**– if a body changes its position with respect to its surrounding then the body is called in a state of motion. For example, a cyclist changes his position every moment with respect to his surrounding then we say that cyclist is in state of motion.

**Q.2 discuss types of motion with examples?**

Ans. There are three types of motion that are given below.

** Translator motion:-** That type of motion in which every particle of a body moves parallel to each other along any path is known as translator motion. For example motion of the car, the motion of aeroplane motion of birds, and the motion of the boat.

** Rotatory motion:**– that type of motion in which every particle of a body moves around a fixpoint is known as rotator motion. For example motion of fan, the motion of the wheel, and motion hand‘s clock.

** Vibratory motion:**– the to and for the motion of body area the same path about its mean position, is known as vibratory motion. For example motion of a pendulum and motion of a mass attached to a spring.

**Q.3 define some terms associated with motion?**

Ans. ** Position:-**The location of an object relative to some reference point is known as the position of that point.

In opposite figure an object is shown at point “p” .by joining “o” and “p” we get op = r

Where r is the distance of “p” from Oregon. P(x,y) is the position of the point

And Q is the angle with x-axis.

** Distance:-**the length of the actual path covered by a body during motion is called Distance it may be straight or curved. It is a scalar quantity and its unit is meter.

** Displacement:-**the shortest distance b/w any two-point is called displacement. In the opposite figure, AD is displacement while ABCD is covered distance.

** Speed:-**distance covered by a body in unit time (1 sec) is called speed.

Mathematical speed = distance covered /time __v = s/t__

It is a scalar quantity and its unit is m/sec.

i. ** Uniform speed:-**if a body covers equal distance in equal interval of time then the speed is called uniform speed.

ii. ** Variable speed:**– if a body covers the unequal distance in equal interval of time then the speed is called variable speed.

iii. ** Average speed:**– total covered distance divided by total took time is equal to average speed.

**math:-**total covered distance /total time.

__<v> = s/t__iv. ** Instantaneous speed:-**the speed of a body at any particular instant of time is known as instantaneous speed.

**Math:-**vins =