A man (m=85 kg) tries to cross a river by swinging from a 10m long vine. His speed at the bottom of the swing (as he just clears the water) is 8.0 m/s. The man doesn't know that the vine has a breaking strength of 1000N. What calculation would determine if the man makes it safely across the river?
2006-07-12 02:05:57 · 5 answers · asked by RL 1 in Science & Mathematics ➔ Physics
That depends. Are there gators in the river?
2006-07-12 02:08:50 · answer #1 · answered by skipjack 2 · 0⤊ 0⤋
The centripetal force, F, is given by the formula m v v/r.
F = 85 x 8 x 8 / 10 =544 newton.
The centripetal force can also be calculated if the tension in the string is known.
If T is the tension in the string, centripetal force is given by T - mg = (T - 85 x 9.8) = (T - 833) newton..
Therefore (T - 833) = 544.
T =1377 newton.
Since the maximum tension is only 1000 N, the string cannot withstand the tension due to this motion.
2006-07-12 05:08:22 · answer #2 · answered by Pearlsawme 7 · 0⤊ 0⤋
Force= mass times Acceleration. What always helped me in Physics is the acronym G.U.E.S.S which stands for Givens (write them down) Unknowns (what is it asking for? Write it down) Equation (write down an equation that fits) Substitute (plug in your numbers) and Solve.
2006-07-12 02:09:21 · answer #3 · answered by Anonymous · 0⤊ 0⤋
centripetal accn is given by v*2/r.
(v square divided by r)
and centripetal force is mv*2/r
if value of centripetal force (mass multiplied by centripetal accn) is less than 1000N, he makes it safely across.
m=85kg
v=8m/s
r=10m
2006-07-12 02:13:59 · answer #4 · answered by bee111 3 · 0⤊ 0⤋
just use Newtons Laws of motions and formulae for centiprital force..
keep caution when equating the forces as one wrong sign can change the answer.
2006-07-12 02:12:55 · answer #5 · answered by AKS 2 · 0⤊ 0⤋