Problem does not make sense km/h at m/s?

[physicshelpme]

problem does not make sense km/h at m/s??

1. A van is traveling at 80 km/h at 25 m/s undergoes uniform deceleration when the brakes are applied, slowing to 50 km/h at 10 m/s after 2.1 s. (a) what is the deceleration? (b) How far does it travel during this period? (c) How much farther does it travel before stopping if deceleration remains constant?

Variables= i don't understand what is meant by 80km/h at 25m/s and 50km/h at 10m/s
vi=25m/s? vf=10m/s? t=2.1s 1)find=-a? 2)displacement=? 3)at vf=0 displacement?

Homework Equations

1)i used d=(vi+v2)/2 x t
2)vf=vi+at to find acceleration
3)know how to compute but didnt because I am unsure of my answer what to do with 80km/h what does this mean? please help

The Attempt at a Solution

d=37m
a=-7.14m/s^2

 

[adjacent]

Welcome to PF
Is that really the question?Name of the textbook?

 

[physicshelpme]

yes

yes that's the questions its a homework problem from a document i don't understand what he means by km/h at m/s ?

 

[SteamKing]

IMO, it looks like a rather clumsy attempt at converting 80 km/h to the equivalent velocity of 25 m/s, etc..

 

[physicshelpme]

yes, that's what i initially thought, i was thinking that at an initial velocity of 85km/h it changes 25m/s but that does not even make sense because how can velocity change a velocity wouldn't it have to be aceleration

 

[adjacent]

I think you should use either km/h or m/s in that problem.

 

[physicshelpme]

ya that's what i wind up doing thanks man

 

[Redbelly98]

It's weird that 80 and 50 kph convert to 22 and 14 m/s, which is off from the m/s values given in the problem. Or, 25 and 10 m/s would convert to 90 and 36 kph. So we would expect two different answers, depending on whether the kph or the m/s values are used -- unless the distances turn out to be the same by sheer coincidence.

As SteamKing said, it's a clumsy attempt at conversion, if that was the the intent.