1. Force
1.1. definition: a push or a pull on an object that causes it to accelerate
1.1.1. symbol = F
1.1.2. units = N (newtons) = (Kg*m/s^-2)
1.1.3. vector quantity
1.2. types of forces
1.2.1. contact forces
1.2.1.1. tension (T)
1.2.1.2. friction (f)
1.2.1.3. normal force (N)
1.2.1.4. applied force (Fapplied)
1.2.2. non contact forces
1.2.2.1. electrostatic force
1.2.2.2. gravitational force (Fg)
1.2.2.3. magnetic force
1.3. newtons laws of motion
1.3.1. 1st law - law of inertia - an object stays at rest or in constant motion unless acted on by an external force.
1.3.1.1. if Fnet = 0 Anet = 0
1.3.2. 2nd law - the acceleration of an object is directly proportional to the net force and inversely proportional to its mass
1.3.2.1. Fnet = ma (force causes acceleration)
1.3.3. 3rd law - for every action force there is an equal and opposite reaction force (force pairs)
1.3.3.1. force pairs never occur on the same object, and the forces must have equal magnitudes.
1.4. friction
1.4.1. static friction - prevents motion
1.4.2. kinetic friciton - opposes motion
2. Momentum
2.1. definition: the product of mass and velocity
2.1.1. equation - P= mv
2.1.2. units - kg*m/s
2.1.3. vector quantity - direction is same as velocity
2.2. impulse
2.2.1. change in momentum caused by a force acting over time
2.2.1.1. J=f*change in T = change in p
2.2.1.2. units - N*s or Kg*m/s
2.2.2. area under a force time graph = impulse
2.3. law of conservation of momentum
2.3.1. in a closed system with no external force acting, total momentum remains constant
2.3.1.1. pinitial = pfinal
2.3.2. applications
2.3.2.1. explosions
2.3.2.1.1. momentum before explosion = momentum after explosion
2.3.2.1.2. objects move in opposite direction with equal and opposite momentum
2.3.2.2. collisions
2.3.2.2.1. elastic collisions
2.3.2.2.2. inelastic collisions
2.4. graphical representations
2.4.1. force-time graph
2.4.1.1. area under curve = impulse (J)
2.4.1.2. steep gradient = large force/short time
2.4.2. momentum-time graph
2.4.2.1. gradient = net force
2.4.3. velocity-time graph
2.4.3.1. gradient = acceleration
2.4.3.1.1. both can be used to analyse momentum changes
2.4.3.2. area under graph = displacement
2.5. applications
2.5.1. rocket propulsion (newton's 3rd law) - expelling gas backwards causes object to move foreards - conservation of momentum
2.5.2. car crashes - air bags and crumple zones decrease impact force by increasing F/t
2.5.3. guns recoiling - momentum = conserved