quote:
You mean I will role down a hill at the same speed regrdless of the slope? you obviously didn't understand how I was applying the grade to the formula.
—RiVeRraT
Acceleration due to gravity is constant. However, you will roll faster down a hill the steeper it is. This is because while the strenght of gravity is constant, it has a direction (toward the center of the earth). In a slope, it points partially into the ground and partially 'down' the slope.
Note that regardless of how steep the slope is, gravity can only contribute from 0 to 9.8m/s^2 acceleration. If the slope is vertical, it's basically a free fall.
I think you got the right idea but expressed it strangely.
Same with the Uk bit. Uk itself is constant (given in the problem). It's the force between the car and the road that can change.
Also, your initial speed formula is off. You need to take the square root of that to get v.
The formula starts as v^2 = 2*g*d*Uk. You should always double-check the units (v must be m/s). g*d is in m^2/s^2.
This is a perfectly good formula for flat ground, but it's probably better to start from scratch instead of modifying it when you have a slope.
This message has been edited by Melchior, 09-24-2004 02:24 PM