The acceleration-time graph of a particle is a straight line joining (0,2)(0,2)(0,2) to (4,6)(4,6)(4,6), where time is in seconds and acceleration is in m s−2\text{m s}^{-2}m s−2. The initial velocity is 3 m s-1.
Write down an expression for the acceleration in terms of ttt.
Find the velocity when t=4t=4t=4.