Motion Notes

• Rate of change of position i.e. rate of displacement with time is called velocity.

• Velocity can be positive, negative or zero. But speed can be positive or zero but it cannot be negative.

[Where 'S' is the distance covered and 't' is the time taken]

SI unit of velocity is m/s (meter/second).

[∵ SI unit of distance is meter and that of time is second]

• Let an object moving with an initial velocity 'u' attain a final velocity 'v' in time 't', then acceleration 'a' produced in the object is

(Acceleration = Rate of change of velocity with time)

Unit of acceleration:

• The variable quantities in a uniformly accelerated rectilinear motion are time, speed, distance covered and acceleration. Simple relations exist between these quantities. These relations are expressed in terms of equations called equations of motion.

Equation of uniformly Accelerated motion:

• There are three equations for the motion of bodies that travel with a uniform acceleration.

1. First equation of motion: The first equation of motion is v = u + at. It gives the velocity acquired by a body in time t.

Let the initial velocity of a body be ‘u’.

It is subjected to a uniform acceleration ‘a’ after time ‘t’. let the final velocity ‘v’.