PH1 Kinematics UVAXT Equations

Vectors & Scalars Vectors e.g. displacement, velocity have a direction, and a magnitude, are a straight line. e.g. 3ms -1 to the East Scalars e.g. distance, speed have magnitude, can be along a non-straight line. e.g. the car travelled 1425m from door-to- door

Vectors & Scalars Distance & Displacement

Speed or Velocity?

Units Distance/displacement: meters (m) Speed/Velocity – distance moved per second = (meters) per second (m/s or ms -1 ) Acceleration – change in speed per second = (meters per second) per second = (m/s)/s = m/s 2 or ms -2

Velocity-time graphs time velocity t u v Gradient = acceleration Area = displacement

Other graphs Displacement-Time: gradient = instantaneous velocity Acceleration-Time: area underneath = final velocity Now try some questions…

UVAXT equations v = u + at x = ut + ½at 2 x = vt – ½at 2 v 2 = u 2 + 2ax x = ½(u+v)t Only when a is constant!

Questions From the worksheet:

UVAXT Questions Work out initial conditions Find out which quantity you are calculating Find out which quantity you don’t need. Identify the correct equation Do the maths

Example A car accelerates from rest at 0.4ms -2 for 15s. How far does it go? x = ut + ½at 2 x = (0)(15) + 0.5(0.4)15 2 = 45m Work out initial conditions Find out which quantity you are calculating Find out which quantity you don’t need. Identify the correct equation Do the maths UVAXT ?

You may need the square root formula

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