Euqation of kinematics in two dimensions

[pookisantoki]

Fans claim that Michael Jordan is able to jump and remain in the air for two full seconds from launch to landing. Evaluate this claim by calculating the maxium height that such a jump would attain. For comaprsion, Jordan's maximum jump height has been estimate at about one meter.
Y=1meter
t=2second
Ay=-9.80
Vy=0
Voy??

I used Vy=Voy + Ay*t
0=Voy+-9.8 *2
Voy=19.6

But it's wrong...not sure what to do from here...

 

[Delphi51]

I used Vy=Voy + Ay*t
0=Voy+-9.8 *2
Voy=19.6

This is very close, but you have to be careful to be clear on what part of the motion you are working with. The 2 seconds is for the full flight - up and down. A final velocity of 0 is for half the flight - just the up part. Choose one or the other for all quantities and you'll get your answer!

Since you are interested in finding the height, you might prefer to use a distance formula. You'll need to find the initial velocity first if you tackle the "up" part with the distance formula, but if you do the down part you of course know the initial velocity.

 

[pookisantoki]

So that would just make Voy 9.8...?

 

[Delphi51]

Yes.