Sec2 Science Physics Notes

Force, Pressure and Speed

FORCE • A force is a pull or push • Instrument to measure forces: Spring Balance • SI unit for force: Newton (N) • Two type of forces: Contact and non-contact

|Contact forces |Non-contact forces |
|Frictional force |Gravitational force |
|Tensional force |Electrical force |
|Normal force |Magnetic force |
|Air resistance | |
|Applied force | |

• Contact force requires the force to have physical contact directly with the object. • For example, when a person pushes a door, the force he applied is in contact with the object

• Non-contact force does not require the actual physical contact with an object. • For example, a permanent magnet attracts an iron bar when it is placed close to the bar.

Effects of a force ▪ Makes an object speed up ▪ Makes an object slow down ▪ Changes the direction of movement of an object ▪ Changes the shape of an object ▪ Causes a stationary object to move ▪ Make a moving object stop

Types of forces
GRAVITY
▪ Gravity is a non-contact force ▪ It is commonly known as gravitational force ▪ The earth and moon have gravitational force. They pull all objects towards them when the object is placed in their gravitational fields.

▪ Gravitational field is a region which an object will experience the pulling force of the