Frank kicks a soccer ball off the ground and in the air with an initial velocity of 30 feet per second. Using the formula H(t) = −16t2 + vt + s, what is the maximum height the soccer ball reaches?

14.1 feet

13.7 feet

13.2 feet

15.2 feet

Question

Frank kicks a soccer ball off the ground and in the air with an initial velocity of 30 feet per second. Using the formula H(t) = −16t2 + vt + s, what is the maximum height the soccer ball reaches?

 14.1 feet

 13.7 feet

 13.2 feet

 15.2 feet

anonymous · Answer

ok 
will use calculus based approach

anonymous · Answer

take derivative
h'(t)=-32t+v

anonymous · Answer

set it equal to zero to get the critical point

anonymous · Answer

-32t+v=0
but v=30 ft given
32t=v
32t=30
t=30/32

anonymous · Answer

are you getting this @MeganLewis ??

anonymous · Answer

yes. but t=30/32 doesnt equal any of my choices.

anonymous · Answer

well for that wait a little :P

anonymous · Answer

t=30/32=0.9375

anonymous · Answer

put that value of t=0.9375 in the original equation H(t) = −16t2 + vt + s
and let me know what you got

anonymous · Answer

and yes use v=30 and  s=0 in the above

anonymous · Answer

H(0.9375)=-16(0.9375)^2+30(0.9375)+0

anonymous · Answer

H=14.0625 feet

anonymous · Answer

is it ok??

anonymous · Answer

14.1 is the close one

anonymous · Answer

Okay thank you!

anonymous · Answer

yw:)