Newton's Laws of Motion Question

[Lelex]

okay, so I've tried this problem and I keep getting it wrong. I would really appreciate some help in solving it. Here is the question:


The parachute on a race car of weight 8820 N opens at the end of a quarter-mile run when the car is traveling at 35 m/s. What total retarding force must be supplied by the parachute to stop the car in a distance of 1000m?


I know there is probably some really simple equation to solve it but I just can't seem to get it. What i tried was using the equation Vsquared=Vosquared + 2ad

I got 0=35squared + 2a(1000), a=.6125 and then plugged that into F=ma to get F=900(.6125)=551.25

I am I even on the right track with this? Please help!

 

[radou]

Looks fine to me.

 

[Lelex]

Thanks for looking. I found out the reason I kept getting it wrong was that I forgot the negative sign. It's the silly mistakes that do you in.