Physics question

[LBD]

Galileo.

9.80665 meters per second per second at seal level. Grape or grapefruit.

Zackerly...close to the same density and shape just different size.

[steve_t]

But these objects are not being accelerated by gravity alone, so this does not apply in this case.

In this case the energy is being supplied by an engine. I've assumed the energy output of the engines remains constant in both cases (since that was what was said). If the energy output remains the same, then the two vehicles will not accelerate at the same rate.

OK, engine vs gravity. Both are constant forces at terminal velocity. Both forces only need to battle against resistance to maintain the object's current state.
Your kinetic energy equation tells you how much energy the object possesses. If a 500kg car and a 2000kg car were both travelling at 50km/h, the equation tells you that the heavier car has more energy, and will do more damage when it hits the brick wall. It doesn't tell you what energy is required to maintain velocity
Where's Crazyhorse again?

[crazyhorse]

But the two cars are not falling. The acceleration at the earth's surface has nothing to do with this issue.

These two vehicles are being propelled along a straight line along the earth's surface under their own power.

Terminal velocity will occur when the energy output of the two engines is effectively matched by the energy loss caused by wind resistance and friction.

I think you need to realise you are beaten on this one

[p.dath]

Crossed purposes - some are meaning dropping from the plane - the plane.

Only in simple Newtonian physics in high school would you consider them to fall at the same rate.

In a falling case then terminal velocity will be reached when the kinetic energy being used (or the potential energy being lost - depending on your perspective) matches the energy being lost through wind drag and friction.

[Big Dave]

Zackerly...close to the same density and shape just different size.

Wouldn't matter if it was a cannon ball (as Galileo used). Acceleration due to gravity (without wind resistance) is a constant.

[Indiana_Jones]

Does adding weight effect the maximum velocity of a self propelled body in atmosphere?

Your penis will explode.

And not in the good way.

-Indy

[LBD]

But these objects are not being accelerated by gravity alone, so this does not apply in this case.

In this case the energy is being supplied by an engine. I've assumed the energy output of the engines remains constant in both cases (since that was what was said). If the energy output remains the same, then the two vehicles will not accelerate at the same rate.

Back to the original question.... acceleration is not in question...maximum speeds of the two cars is the question. The both will be the same, if power to propel, rolling and wind resistance are the same....mass (weight he said) will make no difference.

[p.dath]

OK, engine vs gravity. Both are constant forces at terminal velocity. Both forces only need to battle against resistance to maintain the object's current state.
Your kinetic energy equation tells you how much energy the object possesses. If a 500kg car and a 2000kg car were both travelling at 50km/h, the equation tells you that the heavier car has more energy, and will do more damage when it hits the brick wall. It doesn't tell you what energy is required to maintain velocity
Where's Crazyhorse again?

If you talking about an object leaving the atmosphere, or falling from a great height like a plain, then gravity is not constant. It gets stronger as you approach the earth's surface.

Ek=1/2 m v^2

If you know the kinetic energy and the mass, then you can calculate the velocity.

[Big Dave]

Only in simple Newtonian physics in high school would you consider them to fall at the same rate.

In a falling case then terminal velocity will be reached when the kinetic energy being used (or the potential energy being lost - depending on your perspective) matches the energy being lost through wind drag and friction.

The premise of wind resistance was stated. The rate of acceleration remains 9.8m/s/s without it.

Got yer bonce around this one?
http://www.grc.nasa.gov/WWW/K-12/airplane/termv.html

[p.dath]

The premise of wind resistance was stated. The rate of acceleration remains 9.8m/s/s

Got yer bonce around this one?
http://www.grc.nasa.gov/WWW/K-12/airplane/termv.html

The rate of acceleration at the earth's surface - yes. If your trying to calculate the terminal velocity of an object either leaving the surface or approaching it then you need to use something like:

F=1/2 G m1 m2 / r^2

It's hard to write it out in text form.

m1 is the mass of the earth. m2 is the mass of the object escaping from earth. r is the distance between the mid point of the masses. G is the gravitational constant.

One you have the force being exerted you can use:

f=ma

where m is the mass of your object. a is the acceleration - which will vary depending on r above.

[The Stranger:Me]

If you talking about an object leaving the atmosphere, or falling from a great height like a plain, then gravity is not constant.

Ok, I'm confused, what is a large area of flat land doing falling from a great height anyway?

[p.dath]

So I guess if you want the terminal velocity going "up or down" you need to consider that acceleration of the falling/rising body will vary.

If you consider the object to be "flying" horizontally then vertical acceleration will remain constant at 9.8 m/s/s, but because it is moving horizontal the vertical acceleration of gravity wont have a bearing.

[Big Dave]

Ok, I'm confused, what is a large area of flat land doing falling from a great height anyway?

Symptom of living on a massive fault line.

[Metalor]

I won't affect the top speed, but will effect the acceleration.

Those comments about a feather vs. a car falling from a great height:

The only reason the feather falls much slower is because the surface area to weight is much, much larger, so it feels more force (due to friction moving through air) PER unit of mass. If the went to the moon and did the same thing we would see the feather and the car reach the ground at the exact same time (provided the were dropped from the same height.)

[Virago]

Galileo.

9.80665 meters per second per second at seal level. Grape or grapefruit.

Yeah, but where exactly is the seal? And wouldn't he prefer fish?