A car accelerates from rest at 2.2 m/s2.How much time does it need to attain aspeed of 8 m/s?Answer in units of s.

Please read about posting homework. Show us your work, where you are stumped and then we can help.

You need to memorize a few key concepts, such as the definition of acceleration, which equals change in velocity per unit time. Here you know the change in velocity and the acceleration - now calculate the time required.