Work being done on a car

[qw098]

Hi guys,

I made this theoretical question up, and I was wondering what the answer was. I simply changed a few words from a question from TBR but it tests a different concept they were asking for in the question.

What work is being done on a car moving with an increasing speed along straight, level road?

I. No work or any kind is being done.
II. Work is being done on the car.
III. Work is being done by the car.

A.I only
B. II only
C. III only
D. Any combination you care for, just tell me which

Thanks!

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[LoLCareerGoals]

I would say work is being done by some parts of the car on other parts of the car. (assuming there is no one outside the car pushing really hard
So II&III.

 

[milski]

It's a poorly worded question. Either they need to specify work don on the car by which force or that they're asking about the total work done on the car.

If they're asking about total work, it's the same as the change in KE - the total work done on an accelerating car is positive.

 

[sciencebooks]

How I thought through it... Increasing velocity = positive acceleration = force = work...

So some positive work is being done to make the car move, it could be by the car or on the car.

(I guess, yeah, that is exactly what the other two said, i.e. II and III or positive TOTAL work.)