Mechanics Physics12 Equations, relative motion & relative motion Mechanics Physics12 Equations, relative motion & relative motion Equations of motion

Mechanics Physics12 Equations, relative motion & relative motion Mechanics Physics12 Equations, relative motion & relative motion Acceleration =change in velocity time taken for change a = v - u t We can derive four equations of motion... v = u + at rearranging

Mechanics Physics12 Equations, relative motion & relative motion Mechanics Physics12 Equations, relative motion & relative motion s =ut + ½ (v – u) t v - u = at substituting The area under v/t graph = displacement, s total area under graph and rearranging eqn 1... s =ut + ½ at 2 or...

Mechanics Physics12 Equations, relative motion & relative motion Mechanics Physics12 Equations, relative motion & relative motion Average velocity = s t s = ½ (v + u)t 3 3 = v + u 2 s = (v + u) t 2 rearranging... or...

Mechanics Physics12 Equations, relative motion & relative motion Mechanics Physics12 Equations, relative motion & relative motion rearranging s = ½ (v + u)tt = v - u a into... s = ½ (v + u)(v – u) 2a = (v + u) 2as = v 2 – u 2 v 2 = u 2 - 2as

Mechanics Physics12 Equations, relative motion & relative motion 4 4 v 2 = u 2 - 2as s = ½ (v + u)t s =ut + ½ at 2 v = u + at 1 1

Mechanics Physics12 Equations, relative motion & relative motion Mechanics Physics12 Equations, relative motion & relative motion Write out s, u, v, a and t s = displacement u = initial velocity v = final velocity a = acceleration t = time If you have any 3 you can calculate the other 2. Examples 1 & 2, p17

Mechanics Physics12 Equations, relative motion & relative motion Person walkingMoving walkway 2 ms ms -1 v of person, relative to the walkway v of walkway, relative to the floor

Mechanics Physics12 Equations, relative motion & relative motion 2 vectors, not in a line3 vectors, not in a line

Mechanics Physics12 Equations, relative motion & relative motion Scale: 1cm = 0.5 ms -1 2 ms -1 3 ms -1

Mechanics Physics12 Equations, relative motion & relative motion Scale: 1cm = 0.5 ms -1 2 ms -1 3 ms -1

Mechanics Physics12 Equations, relative motion & relative motion Key words you should now recognise... Homework: Questions 1 & 2, p17 & Q1,2 and 3, p19