What work is being done on a car moving with a constant speed alone a straight, level road?
I none
II work done on the car
III work done by the car
The answer is II and III.
The reasoning in the book makes the statement: "some kind of work is being done by the car--this is why it moves." It makes the distinction that the net force is zero but there are forces acting. I don't follow. According to entropy a moving object can have no forces acting on it thus it continues to move. W=FD. Thus F = 0 and even though D is increasing W would = 0. . . Or W=deltaKE which would also be 0.
The next question is regarding friction. I decided to assume no friction here and missed it. I missed another theoretical type question where I did assume friction. Neither that or this passage said anything regarding friction. The other question was about a slide and this one is about a car. So when do we assume friction and when don't we . . .
I was doing verbal most of the day so I guess im stuck in "make absolutely no assumption mode."
I none
II work done on the car
III work done by the car
The answer is II and III.
The reasoning in the book makes the statement: "some kind of work is being done by the car--this is why it moves." It makes the distinction that the net force is zero but there are forces acting. I don't follow. According to entropy a moving object can have no forces acting on it thus it continues to move. W=FD. Thus F = 0 and even though D is increasing W would = 0. . . Or W=deltaKE which would also be 0.
The next question is regarding friction. I decided to assume no friction here and missed it. I missed another theoretical type question where I did assume friction. Neither that or this passage said anything regarding friction. The other question was about a slide and this one is about a car. So when do we assume friction and when don't we . . .
I was doing verbal most of the day so I guess im stuck in "make absolutely no assumption mode."