physics- force,masss and momentum

Chapter 9

what is force

anything that causes the velocity of an object to change/anything that causes acceleration

f=ma

define the newton

a newton is the force that gives 1KG an acceleration of 1/m²

what is weight

the force of the gravity acting on it 

W=mg

what is momentum

mass x velocity

p=mv

momentum is a vector quaility ,the direction of momentum is the direction of velocity 

what is newtons first law of motion?

every body will remain at in a state of rest or travelling at a constant velocity unless an unbalanced external forces acts on it

what is newtons second law of motion?

when an unbalanced external forces acts ona body the rate of change of the body,s momentum is directly proportional to the force and takes place in the direction of the force

what is newtons third law of motion?

every action has an opposite and equal reaction

what s friction

friction is a force that opposes one surface sliding along another

what is terminal velocity?

when the weight is equal to the air resistance and falls at a constant velocity

what is the princaple of conservation of momentum

the total momentum of two bodies is equal to the total momentuum after the interaction provided no external force acts on the system of bodies

momentum before= momentum after 

m₁u₁+m₂u₂ =m₁v₁+m₂v₂