a boy on a bike ROLLS down a hill to a cliff over water. the hilltop was 50 meters above the cliff and the cliff was 25 meters above the water. how far away does he land in the water?
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the hilltop was 50 meters above the cliff
let speed be v when he shoots of the cliff
PE at top = mgh = 50 mg
KE at cliff = 0.5 * mv^2
50mg = 0.5 mv^2
v = sq root [100g]
v = 31.32 m/s
vertical motion at cliff
s= ut + 0.5 *gt^2
25 = 0 + 0.5 * 9.81 * t^2
t = 2.2576 s
d - distance he lands
d= v * t
d = 31.32 * 2.2576
d = 70.71m ---answer
from the foot of cliff
let speed be v when he shoots of the cliff
PE at top = mgh = 50 mg
KE at cliff = 0.5 * mv^2
50mg = 0.5 mv^2
v = sq root [100g]
v = 31.32 m/s
vertical motion at cliff
s= ut + 0.5 *gt^2
25 = 0 + 0.5 * 9.81 * t^2
t = 2.2576 s
d - distance he lands
d= v * t
d = 31.32 * 2.2576
d = 70.71m ---answer
from the foot of cliff