Inclined plane car out of gas problem

[angeljunti]

A car traveling at 25.0m/s runs out of gas while traveling up a 22.0 degree slope.
How far up the hill will it coast before starting to roll back down?

i tried doing (2*25m/s)^2 / cos22*-9.8cos68 but that wasn't the right answer...

~help please?

 

[6Stang7]

what equation are you using? have you drawn a force diagram?

 

[Hootenanny]

Alternatively, one could consider the work-energy theorem

 

[Delzac]

When i comes to inclined slope like these part of the g is "filtered" off. Thus Draw out your free body diagram, resolve the g in the direction parrallel to the slope.then use the formula V^2 = U^2 + 2as
Hope it helps.

EDITED version
sry ><

 

[Hootenanny]

Delzac, please do not post complete solutions.

Edit: No problems Delzac

 

[6Stang7]

Alternatively, one could consider the work-energy theorem

most defiantly, that's how i first looked at it. from the looks of it though they haven't started studying energy yet (at least that's what i think) and i was ify on possible jumping ahead.

 

[6Stang7]

well, now that the correct formula has been given, does the car accelerate? if so, how would you find the acceleration rate of the car?

 

[castaway]

When i comes to inclined slope like these part of the g is "filtered" off. Thus Draw out your free body diagram, resolve the g in the direction parrallel to the slope.


then use the formula V^2 = U^2 + 2as



Hope it helps.

EDITED version
sry ><

how can you be sure that the acceleration or retardation here is constant?

 

[Hootenanny]

how can you be sure that the acceleration or retardation here is constant?

Is the acceleration due to gravity (approximately) constant here?

 

[google22]

I got 85m by solving for a then using v^2=v1^2+2ad