0How to use kinematic equations and when to use them?
We all know the 3 kinematic equations which are
S= ut + 1/2 at²
V = u + at
V²= u² + 2as
Many students find it difficult to understand when to use them and how to use them.
Just keep a watch for the following points:
1) The equations are used only when acceleration is constant or zero. So while reading a question check whether a body has constant acceleration which will be directly mentioned in the question or will be indirectly given by saying something like " a constant force acts on the body " (which means constant acceleration since F=ma) or "velocity is constant" ( this means acceleration is zero.
2) If you observe these equations have 5 terms u,v,a,t and S. So many a times when quantities like velocity or acceleration are required for calculating quantities like kinetic energy ( = 1/2 mv²) or Force (=ma) they will give you the other terms. For example lets say you are asked final kinetic energy, to calculate that you will require mass and final velocity (V) but instead of velocity the question has stated the body starts from rest which means initial velocity (u) is zero and time t is given along with acceleration a. By using v=u+at you can easily calculate v and hence Kinetic Energy.
So no matter what the chapter is find atleast 3 terms out of the 5 terms of the equations if you spot them that is the biggest hint for using kinematic equations.
Note : These won't be used in cases where acceleration changes.
