Question

A basketball player jumped straight up to grab a rebound. If she was in the air for 0.80 second, how high did she jump?

A) 3.1 m
B) 0.78 m
C) 1.2 m
D) 0.50 m

Answer 1

after 0.40 seconds, she must have reached her max height
she spends half the time going up and the other half falling down

t = 0.40
vf = 0
a = -9.8

y = vf t - 1/2 a t^2

y = 0 - 1/2 (-9.8) (0.4)^2

y = 4.9 (0.4)^2

Y=0.784

This will be your answer.

Answer 2

-- She went up for 0.4 sec and down for 0.4 sec.

-- The vertical distance traveled in gravity during ' t ' seconds is

D = (1/2) x (g) x (t)²

= (1/2) (9.8 m/s²) (0.4 sec)²

= (4.9 m/s²) x (0.16 s²)

= 0.784 meter ( B )