A bicyclist can cost down a 5 degree hill at a constant 6km/h speed. If the force of friction (air resistance) is proportional to the speed v so that Ffr=cv, calculate:
a)the value of the constant c
b) the average force that must be applied in order to descend the hill at 20 km/h. The mass of the cyclist plus bicycle is 80 kg.
I solved part a(or i think so!) c=459,4 . If anyone tells me the b part, i take A+ at physics. PLZ HELP
2007-01-18 04:39:01 · 5 answers · asked by Anonymous in Science & Mathematics ➔ Physics
a)
I don't think the you got the right c. I get c=11.39
Contstant velocity means force is balanced. The component of weight aligned parallel with surface equals the wind force. You probably made a mistake in resolving the weight component. Note that as the angle goes to zero that component of weight must go to zero.
b) Balance weight (component along plane) and external force with air drag:
Fgravity + Fext = cV
2007-01-18 04:59:13 · answer #1 · answered by modulo_function 7 · 1⤊ 0⤋
a) I disagree with both your answers: about 1/10th of your answer and about 4x times modulo_...'s answer. I agree with modulo_...'s discussion. Rethink it. The units on c will be kg/s.
b) Use c to figure the net force, Fnet, required to counter the wind. Then figure what needs to be added to the downhill component of weight to equal Fnet.
2007-01-18 06:04:19 · answer #2 · answered by sojsail 7 · 1⤊ 0⤋
the galaxies rotate at speeds inconsistent with their obvious mass is due to the fact we do see it all. I am relating to it as being the theoretical Dark Matter. There are very powerful proofs that shows that darkish subject exist. One the is the inconsistent velocity of and obvious mass. darkish subject makes up approximately seventy five% to eighty% of the problem within the Universe...
2016-09-07 21:55:38 · answer #3 · answered by ? 4 · 0⤊ 0⤋
I agree with the other answerer. You need to solve this one yourself, otherwise, you don't deserve an A+.
2007-01-18 04:49:37 · answer #4 · answered by au197_0 3 · 1⤊ 0⤋
If someone tells you the answer, you DO NOT DESERVE an A+ in physics. If you figure it out yourself, you DO deserve the A+... so FIGURE IT OUT YOURSELF.
2007-01-18 04:42:32 · answer #5 · answered by poorcocoboiboi 6 · 2⤊ 0⤋