A car accelerates uniformly from rest to a speed of 76.8 mi/h in 7.62 s. Find the constant acceleration of the car. Answer in units of m/s2

Acceleration = (change in speed) / (time for the change)

= (76.8 mi/hr) / (7.62 sec)

= 10.08 mile/hour-second

That quantity is a perfectly good acceleration, it has the right

dimensions etc, but the question asks for it in units of meter/s²,

so I have to convert it to the equivalent in meter/s².

(10.8 mile / hr-sec) x (1,609 meter/mile) x (1 hr / 3600 sec)

= (10.8 · 1,609 · 1) / (3,600) meter / second²

= 4.83 meter / second² if you round all the numbers as you go

or

4.51 meter/sec² if you use a calculator and don't round anything