kinematics

learnt in methods but practical in physics

location §

• location with reference to the fixed point $0$

displacement & distance §

displacement §

• displacement s is a vector
• $s=\Delta x=x_2-x_{1}1$
• positions are often given as displacements from the origin $0$

distance §

• distance is a scalar
• make sure you’re clear between difference between displacement and distance (scalar vs vector, where distance doesn’t have a direction)
• distance describes total length travelled by particle, whilst displacement is not.

velocity and speed §

velocity §

• velocity v is a vector, describing the rate of change in position
• average velocity over the time interval $[t_1,t_2]$ is $v_{av}=\frac{\Delta x}{\Delta t}=\frac{x_2-x_1}{t_2-t_1}$
• instantaneous velocity is given by: $v=\frac{dx}{dy}=\frac{ds}{dt}$

speed §

• average speed != average velocity
• average speed = distance / time

acceleration §

• vector, describe the rate of change of velocity.
• the instantaneous acceleration a is given by dy/dt