So Work= Kinetic Energy and........ (1 Viewer)

[Twickel]

For a object of mass to come to rest an equal negative kinetic energy/force is required. Correct?

 

[Continuum]

Umm... for an object to be at rest, it has to have 0 kinetic energy and 0 net force. That's what you're asking right...?

 

[Twickel]

It is defined as the work needed to accelerate a body of a given mass from rest to its current velocity. Having gained this energy during its acceleration, the body maintains this kinetic energy unless its speed changes. Negative work of the same magnitude would be required to return the body to a state of rest from that velocity

From wikipedia

Is that saying basically that the negative kinetic energy/work is required to bring the object to a rest?

And also Kinetic energy= work ?

 

[Captin gay]

Uh no.. The difference in the final and initial kinetic energies equals the work done on an object -- by the conservation of energy.

W = K2 - K1.

 

[Twickel]

Im doing an experiment so my car always starts from rest so its K2-0 right?

 

[Captin gay]

yes..

 

[Twickel]

So then kinetic energy= work in my case and the work/kinetic energy required to bring the car to a rest is equal negative kinetic/work ????

 

[Captin gay]

No.. the work done by the external agent which pushes the car is positive work.

 

[Twickel]

egative work of the same magnitude would be required to return the body to a state of rest from that velocity from wiki

what does that mean then?

 

[Captin gay]

Means that you'd need an equal amount of frictional work (= to the difference in kinetic energies) to get the car to stop.

 

[Twickel]

So you excelled?

 

[Captin gay]

Huh?

 

[Twickel]

Your in year10 and you know all of this. So .......

 

[Captin gay]

Sorry, I'm actually in 2nd Year uni doing Electrical Engineering. I never did the HSC Physics course

 

[Mumma]

Since when did they start teaching energy in year 11 physics? Man I missed out.

 

[Twickel]

I am confused. SO DOES KINETIC ENERGY= WORK if not WILL IT EQAUL KINETIC ENERGY IN MY EXPERIMENT THE CAR ALWAYS START FROM A SPEED OF 0?

 

[Captin gay]

Since when did they start teaching energy in year 11 physics? Man I missed out.

Don't think it would've made much of a difference tbh. Maybe 4-5 marks in Physics 1A

 

[Mumma]

The work done on an object is equal to its change in kinetic energy. Nothing more to it.

 

[Twickel]

So in my exxperiment the car went down a ramp, so should W=K2-K1 = W=K2- 0 because the car was always at rest?

 

[Mumma]

The work done will be the change in kinetic energy. Since it starts at rest then it has no kinetic energy, since KE = (m*v^2)/2

so W = K2