Forces

=Forces=

=A Formula of Force= There is one totally important formula when it comes to forces, **F = ma**. That's all there is, but everything revolves around that formula. "F" is the value of the **force**, "m" is the object's **mass**, and "a" is the **acelleration** that happens. As a sentence. "The force applied to the object equals the mass of the object multiplied by the amount of its acceleration."

There are many forces in the world, and each has a specific purpose. Gravity - this is the force that pulls objects towards the centre of the earth. It stops us floating away. Magnetism - pulls magnetised objects towards other magnetised objects. Thrust - a push force that makes an object move forward. Reaction/support - a force that opposes gravity, when an object is stationary. Friction - when two objects have contact with each other. this is acontact force, and also helps with air resistance. Push/pull - moves an object forward or backwards. Twist - a force that spins/moves an object.

Force is measured in newtons. Weight is a force and is also measured in newtons. Mass is measured in kilograms. Mass is the ammount of matter, whereas weight is the force of gravity on a mass.

-Forces can move objects -Can stop objects -Can change the shape and size of objects -Can make an object accelerate -Can change direction of an object -Can slow objects down.
 * __Effects of forces:__**

Mass does not change on any planet, it stays the same everywhere.

One type is called **sliding friction**. This is when two surfaces slide one over the other. A snowboarder slides over the snow covered slopes using sliding friction everyday.
 * Friction** is a force that opposes motion. Friction acts in a direction opposite to the object's direction in motion. Without friction, the object would continue to move at a constant speed forever. There are different forms of friction.

When an object rolls over a surface, the kind of friction that occurs is **rolling friction**. Skate boarders take advantage of this type of friction all the time. Reducing the amount of friction between the surface and the wheels allow skaters to go really fast.



Friction also occurs in fluids (gases and liquids). This is how a surfer glides over the water or a shark glides through the water. This type is called **fluid friction.

A very good and informative website: http://www.usoe.k12.ut.us/CURR/SCIENCE/sciber00/8th/forces/sciber/intro.htm