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-CH.2- KINEMATICS The study of the motion of the objects without taking into account the cause of their motion is kinematics.
*MOTION AND TIME ARE RELATIVE TERMS. *THEY AREN’T ABSOLUTE TERMS.
5)SPEED AND VELOCITY The speed of a body is the rate of change of distance or the distance traveled by the body in unit time. It is a scalar quantity. We represent it by the small letter ‘u’ or ‘v’ in italics as ‘u’ or ‘v’. If a body travels a distance ‘S’ in time ‘t’ then formula for speed ‘v’ is Speed = Distance / Time or v = S / t S.I. Unit of Speed – Since, S.I. unit of distance is the meter (m) and of time is second (s), thus, the S.I. unit of speed is meter per second or m/s (ms-1).
The speed of a body is the rate of change of distance or the distance traveled by the body in unit time. It is a scalar quantity. We represent it by the small letter ‘u’ or ‘v’ in italics as ‘u’ or ‘v’. If a body travels a distance ‘S’ in time ‘t’ then formaula for speed ‘v’ is Speed = Distance / Time or v = S / t S.I. Unit of Speed – Since, S.I. unit of distance is the meter (m) and of time is second (s), thus, the S.I. unit of speed is meter per second or m/s (ms-1).
The velocity of a body is the displacement of the body in unit time or the distance traveled by it in a unit time in a particular direction or the rate of change of displacement of a body. It is a vector quantity. We represent it by the small letter ‘u’ or ‘v’ in bold as ‘u’ or ‘v’. If the displacement of a body is ‘S’ in time ‘t’ then then formula for velocity ‘v’ is Velocity = Displacement / Time or v = S / t S.I. Unit of Velocity – As S.I. unit of both distance and displacement is the same i.e. meter (m). Therefore, S.I. unit of both velocity and speed is meter per second or m/s (ms-1).
Note: For velocity, both magnitude and direction need to be specified. The two bodies moves with same velocities, when they move with the same speed and in the same direction. However, if both are moving at the same speed in an opposite or any other direction, then they are said to be moving with different velocities.
-UNIFORM SPEED AND VELOCITY A body is said to be moving with a uniform speed when there is no change in speed with time. Or A body is said to be moving with a uniform speed when the rate of change of distance is the same throughout its motion. Or A body is said to be moving with a uniform speed if it covers equal distances in equal intervals of time. Examples of uniform Speed: 1. 2. A car cruising on a highway with its speed locked on, A ball rolling on a frictionless horizontal surface, etc
A body is said to be moving with a uniform velocity when there is no change in velocity with time. Or A body is said to be moving with a uniform velocity when the rate of change of displacement is uniform throughout its motion. Or A body is said to be moving with a uniform velocity if it travels equal distances in a particular direction, in equal intervals of time. Examples of uniform velocity: 1. 2. A car cruising on the highway towards the north with its speed locked on, A ball rolling on a frictionless horizontal surface in any particular direction, etc.
NUMERICALS 1.A vehicle is moving at 15m/s and then accelerates to 40m/s on 8s. Find (a)acceleration (b)distance that the vehicle travelled over this time. 2.A car is travelling at a speed of 80m/s and is brought to rest in 3m by applying brakes.if the same car is travelling with 120m/s,find the distance in which it can be brought to rest. 3.A body starting from rest with uniform acceleration of 6ms-2.What will the speed of the body be after 3s. 4.A car travels along a straight road to the east for 100m in 4s,then to the west for 50m in 1s.Find the average speed and average velocity.
