Is initial energy (KE and PE) has to equal the KE at impact.
KEimpact=PEorig+KEorig
1/2 m vf^2=mgh + 1/2 m vi^2
solve for vf.
Notice mass divides out, you know h=3, vi=1.8m/s, and g is Earth's gravitation field (9.8N/kg)
"A diver springs upward with an initial speed of 1.8 m/s from a 3.0 m board. Find the velocity with which the diver strikes the water."
Help please!
3 answers
How far above the board will he go?
v = Vi - 9.8 t
0 = 1.8 - 9.8 t
t = .184 seconds until he stops at the top
how far up above the board was that?
h = 0 + 1.8 t - 4.9 t^2
h = 1.8(.184) - 4.9(.184^2)
= .331-.165 = .166 meters above the board
so he falls 3+.166 = 3.166 meters
3.166 = 4.9 t^2
t = .804 seconds falling from top
v = 0 - 9.8 (.804)
= -7.88 meters/second
v = Vi - 9.8 t
0 = 1.8 - 9.8 t
t = .184 seconds until he stops at the top
how far up above the board was that?
h = 0 + 1.8 t - 4.9 t^2
h = 1.8(.184) - 4.9(.184^2)
= .331-.165 = .166 meters above the board
so he falls 3+.166 = 3.166 meters
3.166 = 4.9 t^2
t = .804 seconds falling from top
v = 0 - 9.8 (.804)
= -7.88 meters/second
Thank you! I got it!
2 answers