How much work must be done to stop a 1500kg car traveling at 80km/h

Question

3psilon · Answer

It's kinetic energy right? So just (1/2)mv^2

anonymous · Answer

@3psilon im looking for work. . .

3psilon · Answer

W = K
Work is measured in joules. Kinetic energy is measured in joules.
So Kinetic energy is work

3psilon · Answer

So it would take a -K amount to stop this object. According to the work energy theorem

anonymous · Answer

@3psilon when i did (1/2)*1500*80^2 my answer was wrong. . .

3psilon · Answer

Maybe convert it to m/s since that is the units of v

3psilon · Answer

Work - energy theorem states that W = K(final) - K(initial). So we want the K(final) to be zero since we want it to stop. Then just plug in K(initial) and that is your answer .

3psilon · Answer

W(total)**

3psilon · Answer

You get it @TrentEastwood ? Was your answer correct?

anonymous · Answer

@3psilon I got it wrong *sigh*

3psilon · Answer

Really? Everything we're doing is right? Is it not? What is the answer?

anonymous · Answer

@3psilon the answer was -3.7*10^5

3psilon · Answer

What number are you getting? I'm getting the calculation correctly

anonymous · Answer

@3psilon can you draw out what you did for me?

3psilon · Answer

Sure thing

3psilon · Answer

|dw:1350611778632:dw| @TrentEastwood