PHYSICS - MOTION

PHYSICS - MOTION

Motion in physics refers to movement of object from one point to another. The study of motion enable us to understand how fast a body is moving and describe other characteristic attributed to its motion.

When a body moves from point A to point B, we say the body has undergone motion.

Types of Motion

There are four types of motion.

1. Linear motion - this refer to movement of a body from one point to another on a straight line.
2. Random motion- This type of motion is such that the direction of movement of object is constantly changing with time. An example of this type of motion is the movement of smoke within a room.
3. Circular motion - it refers to motion of a body along a circular path for instance the earth rotating around the earth.
4. Oscillatory motion - this is motion of body to and fro a given point.For instance a loaded spring balance.

Oscillatory motion - Google.                   Random Motion of Smoke particle- Google

Terms used in motion

Distance-  Distance is any of length between two point or more points.Distance gives us an idea about how far two points are from each other,it is . The SI unit of distance is meter(m). Distance is a scalar quantity.

Displacement- Displacement refers to distance traveled in a specified direction. It talks about the distance of movement as well as the direction of the movement in that distance, it is referred to as displacement.Displacement is a vector quantity.

Speed- This is the measurement of distance and the time taken to cover the distance. It is simply the rate of change of change of distance with time.

Speed = distance/ time, the unit of speed is m/s or ms-1 pronounced  meter per second, because it is the unit of length dividing the time. Speed is a scalar quantity. Velocity - Velocity is the rate of change of displacement with time.It the speed traveled in a specified direction. It has the same unit as speed. It is a vector quantity.

Acceleration - Acceleration is the rate of change of velocity with time. When an object changes it speed within an interval of time, it is said to accelerate. If a body at rest begins to move at a low speed and then increases to a higher speed, the body is said to be accelerating.

Equations of linear motion

For a  body acceleration it has need have changed from an initial velocity(u), to a new value of velocity(v) also known as the final velocity,over a given period of time. This implies that the formula for acceleration  from the definition of

acceleration is

 a= (v-u)/t   (1) with unit of m/s2

In actual motion,the speed of a body may vary, then the value for velocity is the average of the initial velocity,u and the final velocity,v. The formula for distance,s is given as

 s= (u+v)/2 x t   (2)

From equation, If we make t the subject of the formula and substitute into equation 2, we get   

 t= (v-u)/a  

Simplifying we get,

v2=u2+2as    (3)

Also from equation, when we make v the subject of formula , we obtain v= u+at and substitute in equation 2 again.

we get

s = ut + 1/2at2    (4)

The four equations of motion are used to solved problems in motion. Summarized as

Equations of motion	Parameter present	Parameter absent
a= (v-u)/t	a,u,v,t	s
s= (u+v)/2 x t	s,u,v,t	a
v2=u2+2as	v,u,a,s	t
s = ut + 1/2at2	s,u,t,a	v