The discussion revolves around calculating the work done by a car engine while traveling a specific distance on a level road, given the car's mass, speed, and friction force. The subject area includes concepts from mechanics, specifically work, force, and motion.
Some participants have identified the correct force to consider for calculating work, specifically the friction force, and have provided calculations based on this understanding. There is acknowledgment of the confusion surrounding terminology related to friction and its implications in the context of the problem.
There is a noted concern about the terminology used in the problem, particularly the use of the term "friction," which some participants feel could lead to misunderstandings regarding the forces at play. Additionally, there are references to seeking further clarification on vector components, indicating a broader interest in related concepts.
(900 kg)(9.81 m/s2) is the forge due to gravity. It acts in a direction perpendicular to the displacement of the car, so that force does zero work.Nanu Nana said:Homework Statement
A car (mass 900 kg) runs 12 km along a level road at a constant speed of 80 km / h. The friction force is 500N. Calculate the work done by the engine
Homework Equations
W= F x displacement[/B]The Attempt at a Solution
W= (900x 9.81) N x 12000m
W=10594800 J
But this is wrong .answer should be 6 x10^6 J
Correct !Nanu Nana said:oh friction force
so
Work = Friction force x (12000m)
W= 500 N x 12000m
W=6 x10^6 Joule
Thank you very much . Where on forum should i ask if i want explanation about vectors components?SammyS said:Correct !
Nanu Nana said:Thank you very much . Where on forum should i ask if i want explanation about vectors components?
Nanu Nana said:Thank you very much . Where on forum should i ask if i want explanation about vectors components?
If it's a from a homework problem or closely related to one, then this is the correct forum.Nanu Nana said:Thank you very much . Where on forum should i ask if i want explanation about vectors components?
Calling the resistance to a car's normal motion simply 'friction' is one of my pet hates. It's so confusing for students. What the question means is some combination internal friction (bearings etc.), rolling resistance and drag. The friction between the tyres and the road is precisely what allows the car to get anywhere. In the context of the problem, it would be acting in the forward direction.Nanu Nana said:A car (mass 900 kg) runs 12 km along a level road at a constant speed of 80 km / h. The friction force is 500N. Calculate the work done by the engine