Hang time

[Addallat]

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A man jumps 2 meters in the air, what is his hang time (time in air)?


A. 0.7 seconds
b. 1.3
c. 2.8
d. 4.0


ahhhh i'm having trouble with these kinematics problems

So logic

displacement = 2 meters
acceleration is gravity (10 m/s^2)
initial velocity is zero
and I need to solve for time

so

X = 1/2 (g) (t^2)

becomes

square root of (4/10) <~~~~ the math is giving me the hardest time

am i setting up this problem right? and if so please help me with the arithmetic

 

[basketballfan]

Your set up seems right to me.

As for the arithmetic, I would do square root of 4 (that would be 2) divided by square root of 10 (around 3, because 3 squared is 9). So you get around 2/3 as time up, but you have to considered time down too so it would be (2/3)*2.

I hope that helps...

 

[Addallat]

ahhhhhh time down can't believe i forgot this. thank you!