SPEED - VELOCITY - FITTER ONLINE NOTE

SPEED & VELOCITY

REST:-

i)- The body occupies the same position with respect to its surroundings at all moments. The body is said to be called at REST. 

MOTION:-

i)- The body it change its position with respect to its surroundings the body is said to be called at MOTION.  

ii)- The body motion may be moves in a straight line or it may be circular when it moves in a curved path. 

DISPLACEMENT:-

i)- When a body is in motion from one place to another, the displacement is the distance from the starting position to the final position. Is called DISPLACEMENT.

VICTOR QUANTITY:-

i)- Vector quantity possesses both magnitude and direction are indicate.

ii)- For example Velocity, Acceleration, Force, Momentum.

SCALAR QUANTITY:-

i)- Scalar quantity possesses only magnitude with no idea of direction.  

ii)- For example Length, Mass, Time, Area, Speed.

SPEED:-

i)- The rate at which an object is changing its place is called its SPEED.

ii)- Speed does not indicate direction.Only magnitude is expressed.

iii)- For Example- A train travels 40 miles in 2 hours then its speed 20 miles per hour, will not show the direction.

iv)- Formula of Speed (S) = Distance covered/Time .

v)- Its Unit is = m/s, km/Hr.mile/Hr.

VELOCITY:-

i)- The rate of speed of an object in a particular direction is called its VELOCITY.

ii)- Both the magnitude and direction are expressed.

iii)-  Velocity  may be goes to linear or angular motion.

iv)- Its Unit is  Metre/sec, km/Hr, mile/Hr(Linear unit) or Radians per second(Angular unit)  

v)- Formula Velocity = Distance traveled in definite direction/time

vi)- Velocity are Two types a)- Final Velocity, b)- Initial Velocity.

ACCELERATION:-

i)- Rate of change of velocity of an object is known as ACCELERATION. 

ii)- It is the change of velocity in unit time.

iii)- Its unit is metre/sec2. It is a vector quantity.

iv)- The Negative acceleration is know as RETARDATION.

v) Formula of acceleration (a) = Change in velocity/time or a= v-u/t

vi)- Formula of Retardation (d) = u-v/t.

Equations of motion:-

u = Initial velocity in metre per second(m/sec) 

v = Final velocity in metre per second(m/sec) 

s = Distance in metre (m) 

t = Time in second (sec) 

a = Acceleration m/sec2 (positive value) R = Retardation m/sec2 (negative value of acceleration) 

Motion under gravity:- 

i)- A body falling from a height, from rest, has its velocity goes on increasing and it will be maximum when it hits the ground.  

ii)- Therefore a body falling freely under gravity has a uniform acceleration.  

iii)- When the motion is upward, the body is subjected to a gravitational retardation.  

iv)- The acceleration due to gravity is denoted with ‘g’. 

Momentum:- 

i)- It is the quantity of motion possessed by a body.

ii)- It is equal to mass of product. 

iii)- The velocity with which it is moving.  

iv)- Unit of momentum will be kg metre/sec. 

v)- Formula is Momentum = mass x velocity .

Circular or Angular motion:-

i)- When a body rotates about an axis, it is said to have angular motion or circular motion.

ii)- Example In circular motion bodies (like shafts, axles, gear-wheels, pulleys, flywheels, grinding wheels) turn with constant speed around its axis. 

iii)- The angular of circular motion is also called Angular velocity or Peripheral speed. 

iv)- Expressed in Metre/sec or Radians per second.

Bodies at rest and in motion(Terms related to brake system):- 

i)- Every vehicle has a brake system.  When brakes are applied on a moving vehicle (with certain velocity) its velocity is reduced and vehicle is decelerated and it stops at a certain distance.  

ii)- For Example:-  This is the decrease in velocity within a certain time. A car travelling at 90 kmph stops after 10 Sec.

iii)- Deceleration(retardation) time The time 10 seconds is called the above time to stop the vehicle.

NEWTON’S LAWS OF MOTION 

Equations of motions under gravity formula

Upward:- V = u – gt , s = ut – 1/2 gt2, u2–v2 = 2gs 

Downward  v = u + gt, s = ut + 1/2 gt2,  v2–u2 = 2gs

FORMULA

i)- v = u + at 

ii)- S = ut + 1/2 at2 and 

iii)- v2 – u2 = 2as 

iv)- v2 = u2 + 2as

v)- average speed (Vm) = 2 x s x n 

vi)- Average velocity = (u+v)/2