A 1D kinematics...help needed!

[Ice-cream]

can some1 help me with this problems?

 

1. Michael Jordan's vertical leap is reported to be 48 inches. What is his takeoff speed? (ans. 4.9m/s)

 

i first converted 48 inches to 121.92cm (inches to cm is inches x 2.54 right?) and then i used v^2 = u^2 + 2as where v is 0, a is -9.8m/s/s, and s is 121.92m. however, the ans. coms to 48.88m/s. can some1 tell me wat's wrong?

thanx

[jordan]

You converted 121.92cm to m before you calculations right?

[Ice-cream]

oooooopsssss!!!!! thanx