- #1
Mr Davis 97
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Homework Statement
A 50 kg woman jumps straight into the air, rising h meters from the ground. What impulse does she receive from the ground to attain this height?
Homework Equations
The Attempt at a Solution
Impulse is defined as a change in momentum. Thus, ##I_{woman} = m(v_f - v_i)##. Since she jumps to some height, we know that her final velocity is zero. Thus##I_{woman} = - m v_i##. We can find the initial velocity with ##v_f^2 = v_i^2 - 2gh##, so ##v_i = \sqrt{2gh}##. Thus, the impulse on the woman from the ground is ##I_{woman} = -m \sqrt{2gh}##.
So the magnitude of this impulse is correct, but apparently my sign is wrong. What am I doing wrong?