Originally Posted by

**fishkeeper** I have this question, but cannot rearrange any of the SUVAT equations to get the answer:

A set of traffic lights covers road repairs on a road. The traffic lights are 80m apart. Assume a car accelerates at 2ms^2 from rest until reaching a speed of 10ms^1 and then travels at a constant speed. What is the least time taken for a car starting from rest at the first set of lights to reach the next set?

****************

S= 80m

U= 0ms^1

V= 10ms^1

A= 2ms^2

T= ?

The answer is 10.5 seconds, the closest I have got is 8.9 seconds by rearranging s= ut + 1/2at^2 into the form of the quadratic formula. Otherwise I have not come anywhere close to the answer, and I dont know how, as Im certain Ive rearranged the suvat equations properly.

Please help

thanks