A cyclist travelling in a straight line increases her velocity from 6.0 m/s to 18 m/s in 4.0 s.
What is her average acceleration?
1.5 m/s21.5\ \mathrm{m/s^2}1.5 m/s2
3.0 m/s23.0\ \mathrm{m/s^2}3.0 m/s2
4.5 m/s24.5\ \mathrm{m/s^2}4.5 m/s2
6.0 m/s26.0\ \mathrm{m/s^2}6.0 m/s2