Question

Say, a car is travelling a constant velocity, which means a=0. By F=ma, F is also 0. Since Work done formula is Force x Distance travelled in direction of force , W=Fs, my work done is also 0. So, question is, if work done is equal to 0, how is it possible that my car is moving ?

Answer 1

i'll try to answer your question

Answer 2

thank you sir :)

Answer 3

The c is still movi, ecauseof its inertia, which states that if a body is at movement it will remain at movement, unless an external force acts on it, meaning the force from the beinning, which was constant or 0, remains at that value, hence change in kinetic energy=0.

Answer 4

The car is still moving ...*

Answer 5

It means, no (external) work was done on moving car!

Answer 6

uhm.. then what does the Work represent ? W=Fs, if W=0 what does that mean ?

Answer 7

Work is done when a force that is applied to an object moves that object

Answer 8

In this case work shall be the same as kineic energy and given that kinetic energy = m(v^2-u^2)/2, it means that the initial and final speed are equal, hence the Kinetic energy becomes 0.

Answer 9

hmm.. this still confuses me as since W = 0 how can the car be moving ? K.E ? but isnt K.E same as W since they are both in Joules

Answer 10

Yes, they are.

Answer 11

what equation should i look at ? P=Fv ? K.E or work ?

Answer 12

the car can moving because its velocity

Answer 13

uhm.. what causes the car to move ? the engine right? the energy provides the car with force or energy ? sorry for being stupid x.x

Answer 14

engine*

Answer 15

It was correct, saying that W=KE=PE=P, all shall be zero. Why? Because remember that the force applied was 0, hence when a body has been initially moving and the force applied to it is 0 at a given distance, their multiplication is equal to zero. Another thing is that this formula might be a bit tricky, because the assumption derived in inertia as I said before is that no external force shall act, meaning there should be no resistance to make the body decellerate. In real life situations, you hardly find a place without resistance. So the assumption is that no force was acting and the body moved in constant speed forever.

Answer 16

You are not being stupid. That is actually the way you should think to deeply analyse and find the reason behind physics theorems. No need to blame yourself.

Answer 17

even thought W=0 , the car is still moving due to inertia ?

Answer 18

uhm.. thanks anyways! :D @Hoslos

Answer 19

Every object in a state of uniform motion tends to remain in that state of motion (rest and moving with a constant acceleration) unless an external force is applied to it. Your car has been initially moving with no work that is done on it

Answer 20

Yes, the inertia is what makes it keep moving.
The way I always put in my mind is that inerta=laziness or persistance.
If you move, you still want to move
If you rest, you will be lazy resting until...

Answer 21

that is Newton's First Law of Motion!