# Physics -Forces

• Forces
• Contact and Non-contact forces
• Scalar quantities only have magnitude and no direction.
• Examples are: speed; distance; mass; temperature; time ect.
• Vectors have magnitude and direction.
• Examples are: force; velocity; displacement; acceleration; momentum ect,
• Forces are either contact or non-contact forces.
• Contact forces are when two objects have to be touching for a force to act.
• Non-contact forces are when the objects don't need to be touching for the force to act.
• When two objects interact, there is a force produced on both objects. An interaction pair is a force that is equal and opposite and acts on two interacting object.
• Resultant forces and Work Done
• A resultant force is the overall force on a point or object.
• Work Done = Force x Distance moved along the line of action of the force
• When a force moves an object through a distance, energy is transferred and work is done on the object.
• W(J) = F(N)s(m)
• Forces and Elasticity
• Stretching; compressing or bending transfers energy
• Extension is directly proportional to force unless the force is great enough.
• F=ke