Lastest Top Kill Bp News
January 3rd, 2012
Comments Off
Archive
Archive for January 3rd, 2012
Q&A: Using energy conservation to find the maximum height?
January 3rd, 2012
Comments Off
Question by : Using energy conservation to find the maximum height?
A 65.0 kg skier approaches the foot of a hill with a speed of 16.0 m/s. The surface of this hill slopes up at 55.0 degrees above the horizontal and has coefficients of static and kinetic friction of 0.750 and 0.250, respectively, with the skis.
Use energy conservation to find the maximum height above the foot of the hill that the skier will reach.
Best answer:
Answer by TBT
initial KE
= 0.5 * 65 * 16^2 J
let h be the maximum height above the foot of the hill that the skier will reach
normal force due to weight
= 65 *g * cos 55
friction force
= 0.25 * 65 *g * cos 55
length travelled
= h /sin 55
final PE + work done due to friction
= 65 * g * h +0.25 * 65 *g * cos 55 * h /sin 55
65 * 9.81 * h + 0.25 * 65 *9.81 * cos 55 * h /sin 55 = 0.5 * 65 * 16^2
637.65 h + 111.59 h = 8320
h = 11.1 m —answer
Add your own answer in the comments!
Cool NUCLEAR POWER images
January 3rd, 2012
Comments Off
Some cool NUCLEAR POWER images:
20110630 Pro Nuclear Power Demo082
Image by JamesReaFotos
Q&A: ion drive and vasimr rockets?
January 3rd, 2012
Question by Random Questions: ion drive and vasimr rockets?
I fully understand how each of these systems operates and I don’t want to get into detail about it, but I wish to know some other information about them. The first is i know that they could travel longer than a conventional rocket but are they faster then the shuttle and by how much? The second is suppose I use a mass driver or a rail gun type launch to get the craft going and then turn on the ion drive will it continue at that speed(don’t take newtons 1 law into affect) or will it add on to the speed of the craft soon after the launch? Finally would a vasimr rocket work inside the earths atmosphere under gravity and air or does it not have enough thrust( same applies to the ion drive)?
Best answer:
Answer by eelfins
The thing about the vasimr is that it’s variable: if you open the choke it gets a lot of thrust with little efficiency. If you narrow it you get a lot of efficiency with little thrust. Lots of thrust is needed in low orbits in order to capitalize on gravitational energy, but in open space high-efficiency is required because there is no gravitational sling-shot. I don’t think a vasimr could be launched from earth’s surface, it would most likely have to be built in orbit.
What do you think? Answer below!