Finding Acceleration: Motorist Travels 0.2km in 45-99km/h

[adoado]

Homework Statement

A motorist enters a freeway at 45km/h and accelerates uniformly to 99 km/h. From the odometer of the car, the driver knows she has traveled 0.2km. Find the acceleration of the car.

Homework Equations

The Attempt at a Solution

I attempted this:

v² = u² + 2as

Substituting the values in I got this:
(99² -45²)/0.4 = a

this gives 19440, so converting to m/sec I think I get 5400 m/sec²

This is definitely not right, any ideas why?

Cheers,
Adrian :)

 

[Doc Al]

this gives 19440, so converting to m/sec I think I get 5400 m/sec²

What units do you think the 19440 would be in? Check your conversion.

The best thing to do is change units to m/s and m before you use them in the formula.

 

[adoado]

Got it! Thanks a bunch!

Cheers,
Adrian