Problem 5.73
A 1.58 m wide, 1.36 m high, 1400 kg car hits a very slick patch of ice while going 19.0 m/s . Air resistance is not negligible.
If friction is neglected, how long will it take until the car's speed drops to 14.0 m/s?
To 9.00 m/s ?
2006-12-14 07:31:03 · 3 answers · asked by physicsmed22 1 in Science & Mathematics ➔ Physics
Good question! The car will slow down due to air resistance (obviously, since that is the only force we're not ignoring). Since the car is massive, ie larger than a raindrop, the primary component of air drag will be the v^2 term. The force is F=kpAv^2, where k is related to how streamlined the car is (in this scenario, I'm guess k=1); p is the density of the air (you can probably use the STP value); and A is the cross-sectional area of the air you are moving (or, the cross sectional area of the car - 1.58*1.36 m^2).
Now that you have a force, you can divide by the car's mass to find acceleration. Integrate this term to find the velocity. You are now left with a differential equation for velocity, which may or may not be analytical. You'll probably want to plug this into some math software like MatLab, Mathematica, Maple, whatever. Hope that helps!
2006-12-14 23:36:10 · answer #1 · answered by woocowgomu 3 · 0⤊ 0⤋
IT WONT! If there's no friction and no outside force slowing it down, It wont stop. It will stay at the same speed. And by the way, that's a very small car. I've seen go-karts bigger than that.
2006-12-14 17:16:09 · answer #2 · answered by jpferrierjr 4 · 0⤊ 1⤋
i don't have equations infront of me, but you should be able to just plug and chug...knowing mass, and delta velocitys.
2006-12-14 17:22:29 · answer #3 · answered by lasersail116480 2 · 0⤊ 0⤋