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Starting from rest, a 2.4x10-4 kg flea springs straight upward. While the flea is pushing off from the ground, the ground exerts an average upward force of 0.42 N on it. This force does 1.5x10-4 J of work on the flea. (a) What is the flea's speed when it leaves the ground? (b) How far upward does the flea move while it is pushing off? Ignore both air resistance and the flea's weight.
6 answers
at takeoff Ke = (1/2) m v^2 = 1.5*10^-4
solve that for v
work done = force * distance
1.5*10^-4 = .42 * distance
solve that for v
work done = force * distance
1.5*10^-4 = .42 * distance
(a) Work = (1/2)MV^2 at takeoff
v = sqrt(2*2.4*10^-4/1.5*10^-4)
= 0.00017888543 j
v = sqrt(2*2.4*10^-4/1.5*10^-4)
= 0.00017888543 j
still not right where am I going wrong?
1.5*10^-4 = (1/2) (2.4*10^-4) v^2
so
v^2 = 3/2.4 = 1.25
v = 1.11 m/s
so
v^2 = 3/2.4 = 1.25
v = 1.11 m/s
I dont get how you got the unit m/s for v.. can you elaborate?