7. Exercises

A football ball is kicked so that its position, in metres, at time t seconds is given by

\displaystyle \mathbf{r}=6t\mathbf{i}+\left( 15t-4.9{{t}^{2}} \right)\mathbf{j}

where \displaystyle \mathbf{i} and \displaystyle \mathbf{j} are horizontal and vertical unit vectors respectively.

a) Find the position of the ball when t = 0, 1, 2, 3 and 4 seconds.

b) Plot the path of the ball.

c) From your plot estimate the horizontal distance travelled by the ball when it hits the ground.