1. Motion for Constant Acceleration

2. Equations of Motion for Constant Acceleration
In this lesson the students are shown how to use a velocity-time graph to develop the equations of motion for constant acceleration.
To give the students confidence, they are sometimes asked to share ideas with a partner.

3. Ans: The gradient gives the acceleration.
We can use a velocity-time graph to find some equations that hold for a body moving in a straight line with constant acceleration.
Suppose when the time is
velocity (ms-1)
the velocity is u. v
Constant acceleration means the graph is a straight line. u
At any time, t, we let the velocity be v. t
time (s)
Remind your partner how to find acceleration from a velocity-time graph.
Ans: The gradient gives the acceleration.

4. We can use a velocity-time graph to find some equations that hold for a body moving in a straight line with constant acceleration.
Suppose when the time is
velocity (ms-1)
the velocity is u. v
Constant acceleration means the graph is a straight line.
v - u u
At any time, t, we let the velocity be v. t t
time (s)
v - u
So,
a = t
From this equation we can find the value of any of the 4 quantities if we know the other 3.

5. v - u a = t a t = v - u  u + a t = v  v = u + a t
We usually learn the formula with v as the “subject”.
Multiplying by t:
a t = v - u
 u + a t = v 
v = u + a t
The velocity, u, at the start of the time is often called the initial velocity.