# Physics- Contact and Non-Contact forces

?
• Contact and Non-Contact Forces
• Vector Quantity
• Vector quantities have a magnitude and a direction
• Lots of physical quantities are vector quantities
• Vector quantities: force, velocity, displacement, acceleration, momentum etc.
• Vectors are usually represented by an arrow - the length of the arrow shows the magnitude, and the direction of the arrow shows the direction of the quantity.
• Velocity is a vector
• Force is a vector quantity
• Scalar Quantity
• Some physical quantities only have magnitude and no direction. These are called scalar quantities
• Scalar Quantities: speed, distance, mass, temperature, time, etc.
• Speed is a scalar quantity
• Contact forces
• A force in which two objects have to be touching for a force to act
• E.g. friction, air resistance, tension in ropes, normal contact force, etc.
• Forces
• A force is a push or a pull on an object that is caused by it interacting with something
• All forces are either contact or non-contact forces
• When two objects interact, there is a force produced on both objects
• An interaction pair is a pair of forces that are equal and opposite and act on two interacting objects.
• Non-contact forces
• A force in which objects do not need to be touching for the force to act
• E.g. magnetic force, gravitational force, electrostatic force, etc.