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
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