10.0.0. MOTION

10.0.0.  MOTION
Definition of motion:
Motion is the time rate of change of position of an object.
Kinematics is the branch of mechanics that deals with the motion of an object without reference to the force that caused the motion..

CAUSES OF MOTION:
Force is the agent that causes motion. An object moves when a force act on the object.
EFFECT OF FORCE:
The effect of force that act on an object is either to make the object move or stop moving.
TYPES OF MOTION :
1) Random motion :
This is the motion of an object in a random manner or in an irregular direction. The direction of the motion of the object can not be explained.

EXAMPLES OF RANDOM MOTION
• Motion of particles
• Motion of a bee or mosquitor
• Motion of insect
• Brownian motion, etc


2) Translational motion:
This is the movement of a rigid body from one place or point to another without rotation. Each part of the body that undergo the motion follow the same path and remained fixed to one another.

EXAMPLES OF TRANSLATIONAL MOTION
• Motion of a car from one point to another
• Motion of a bee from one flower to another
• Motion of a man from one place to another
• Motion of animal from one place to another

3) Rotation motion :
This is a type of motion whereby all points in then body of the object move in a concentric circles and the central of the circles lie at the same axis of rotation.
Diagram here:


EXAMPLES OF ROTATIONAL MOTION
• Rotational motion of the earth
• Rotational motion of blades of electric fan
• Rotational motion of car wheel
• Rotational motion of hands of clock
4) Oscillatory motion:
This is the to and fro motion of an object about a fix point or about its equilibrium position.
DIAGRAM HERE:

EAMPLES OF OSCILLATORY MOTIONS
• To and fro motion of simple pendulum
• To and fro motion of loaded test tube in water
• To and fro motion of a mass hanging on pring
• To and fro motion of a rocking chair
• To and fro motion of diving board


5) RECTILINEAR MOTION
This is the motion of an object in a straight line.

EXAMPLES OF RECTILINEAR MOTION
• Linear motion of a car
• Motion of a rocket from one place to another.
6) Spin motion:
This is the rotational motion of an object about a fixed point.

Examples of spin motion:
• Motion of acone on its vertex
• Motion of a pin on its pointed mouth
• Motion of a pen on its pointed mouth

7) Relative motion:
This is the motion of one object in relation to another. The  two objects may be moving in the same direction or in opposite directions.
It can also be defined as the continuous change of position of an object with respect to another object or to a reference fixed point.

How to find the relative velocity of two:
• If the two objects are moving in the same direction, you add their velocities to get the relative velocity.
• If the two objects are moving in opposite directions, you subtract their velocities to get the relative velocity.

Worked Example:
A man sit inside a moving bus that is moving with a speed of 25m/s. If the speed of the man is 12m/s, calculate his velocity relative to the earth when the man walk to the driver at the front, when he walk back to his sit.

Solution :
Bus speed = 25m/s
Man speed = 12 m/s
When the man walk to the front, his speed is increase by the amount of the bus speed.
Therefore,
Man speed when he walk to the front = man speed + bus speed
                                                                     = 12m/s + 25 m/s = 37 m/s
When the man walk back to his sit, his speed is in the opposite direction to his motion.
Therefore,
Man speed when he walk back to his sit = bus speed – man speed
.                                                                         =  25 m/s – 12 m/s = 13 m/s

Also, we can find the relative velocity of two objects that are moving in a perpendicular directions. We find the relative velocity by drawing a vector triangle. The hypotenuse of the triangle is the relative velocity of the objects.

Worked example:
Two trains travel with velocities 5 m/s and 7 m/s due north and west respectively. Calculate their relative velocity.

Solution:
Draw a vector triangle thus
The sides of the triangle represent the speed of the trains.
While the hypotenuse represent the relative velocity.
Use Pythagoras formula to find RV thus
Rv^2 = 5^2  + 7^2
RV^2 = 25 + 49
RV^2 = 74
RV = √74
Relative Velocity = 8.60m/s .
As simple as that. Remember that the direction of motion
of the two objects must be at right angle to one another.