physics project work

Force and laws of motion

forceA push or pull on a body is called FORCE .Forces are used in our everyday actions like pushing , pulling , lifting , stretching , etc.

Effects Of Force

A force cannot be seen . A force can be judged only by the effects which it can produce in various bodies (or objects) around us . A force can produce the following effects :

1. A force can move a stationary body .2. A force can stop a moving body .3. A force can change the speed of a moving body .4. A force can change the direction of a moving

body .5. A force can change the shape and size of a

body .

Balanced And Unbalanced FORCES

Forces are of two types :• BALANCED FORCES

• UNBALANCED FORCES

Balanced

ForcesIf the resultant of all the forces acting on a body is zero , the forces are called balanced forces .• Balanced forces doesn't change the position of the body and appears as if no force is acting on it •Though , balanced force can’t produce motion on a stationary body or stop a moving body , but it can change the shape of the body .

Unbalanced ForcesIf the resultant of all the forces acting on a body is not zero , the force is called unbalanced force . Unbalanced forces can do the following:• Move a stationary object .• Increase the speed of a moving object .• Decrease the speed of a moving object .• Stop a moving object .•Change the shape and size of the object .•If there were no unbalanced force of friction and no air resistance , a moving bicycle would go on moving forever . •.

Sir Isaac NewtonSir Isaac Newton was one of the greatest scientists and mathematicians that ever lived. He was born in England on December 25, 1643. He was born the same year that Galileo died. He lived for 85 years.While Newton was in college he was writing his ideas in a journal. Newton had new ideas about motion, which he called his three laws of motion. He also had ideas about gravity, the diffraction of light, and forces. Newton's ideas were so good that Queen Anne knighted him in 1705. His accomplishments laid the foundations for modern science and revolutionized the world. Sir Isaac Newton died in 1727.In this lesson you will develop an understanding of each of Newton's Three Laws of Motion.

Newton’s First Law of Motion

An object at rest will remain at rest unless acted on by an unbalanced force. An object in motion continues in motion with the same speed and in the same direction unless acted upon by an unbalanced force.

INERTIA : It is the property of a body due to which it resist a change in its state of rest or of uniform motion .

Momentum

Momentum of a body is defined as the product of its mass and velocity .

Momentum = massXvelocity

Or, p=mXvIt is a vector quantity

having both magnitude and direction .

SI UNIT = kg.m/s

Newton's Second Law of Motion

Acceleration is produced when a force acts on a mass. The greater the mass (of the object being accelerated) the greater the amount of force needed (to accelerate the object).

the Second Law gives us an exact relationship between force, mass, and acceleration. It can be expressed as a mathematical equation: 

F = maOr, Force = mass x velocity

Newton's Third Law of Motion

For every action there is an equal and opposite re-action.

This means that for every force there is a reaction force that is equal in size, but opposite in direction. That is to say that whenever an object pushes another object it gets pushed back in the opposite direction equally hard. 

Law of conservation of momentum

• When two or more bodies act upon one another, their total momentum remains constant provided no external forces are acting.

• Momentum is neither created nor destroyed.

• Can we apply this law for a collision between two vehicles? Yes, we can! This law is applicable for all types of collisions.

Made By Sanaa SialStudent of class IX

D.AV. ACC Public School , Katni