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physic free fall?
A skier is gliding along at 2.5 m/s on horizontal, frictionless snow. He suddenly starts down a 16° incline. His speed at the bottom is 15 m/s. (a) What is the length of the incline?
(b) How long does it take him to reach the bottom?
1 Answer
- Anonymous1 decade agoFavorite Answer
Let:
s be the length of the incline,
m be the mass of the skier,
t be the time of descent.
(a)
His KE at the top is:
m(2.5^2) / 2 J
and his PE is:
m(9.81)s sin(16) J
His KE at the bottom is:
m(15^2) / 2 J
Therefore:
m(2.5^2) / 2 + 9.81ms sin(16) = (15^2)m / 2
s = (225 - 6.25 ) / 2 *9.81 sin(16)
= 40.4m.
(b)
His acceleration down the slope is:
9.81 sin(16) m/s^2
15 = 2.5 + 9.81t sin(16)
t = (15 - 2.5) / 9.81 sin(16)
= 4.62 s.