Pushing force

Thrust

Pulling force

Tension

Resistive force

Friction

Rebound force

NCRF

Gravity modelling assumption

Vertical and CONSTANT

modelling assumption about surfaces

Smooth has NO FRICTION

Modelling assumptions about particles

Has negligible dimensions

Modelling assumptions about ‘light’ objects

0 mass

SUVAT without s

a = v-u /t

SUVAT without a

S = t (v+u)/2

SUVAT without u

S = vt - 1/2 at^2

SUVAT without v

S = ut + 1/2 at^2

SUVAT without t

V^2 = u^2 + 2as

displacement to velocity to acceleration

Differentiate

Acceleration to velocity to displacement

Integrate

r = (position vector)

r = r0 + s

s = displacement

r = original position

SUVAT not used in 2D

v^2 = u^2 + 2as because squares aren’t vectors

Modelling assumptions with projectiles

No air resistance,

Move freely under gravity,

No spin

time of flight =

2u sinθ / g

Horizontal displacement =

u^2 sin 2θ / g

Time reached maximum height = (in terms of time)

Time of flight / 2

Maximum height

u^2 sin^2 θ / 2g

NI definition

an object at rest will stay at rest and an object moving at a constant VELOCITY will remain at a constant velocity unless a RESULTANT force acts upon it

Rf =

F1 + F2 + F3 …

NII definition (maths)

The RESULTANT force acting on a body is EQUAL to the PRODUCT of the mass of the body and its acceleration and force and acceleration are in the same direction.

F = ma

NIII definition

The force exerted by body A on body B is equal in magnitude to the force exerted by body B on body A but in an opposite direction

Find tension between two bodies connected by a string

Equal magnitude and opposite directions from each box

THEREFORE can model 2 particles as ONE PARTICLE

equation for pulleys

NII and SUVAT

Direction of tension in pulley system

Always TOWARDS pulley and OPPOSES WEIGHT