On earth, the height, h metres, of an object fired upward from the earth's surface at 48m/s is described by the equation h=48t-16t^2 where t seconds is the time since the object was fired upward.
Determine:
A.) the maximum height of the object
B.) the times at which the object is 32m above the ground
C.) the time at which the object hits the ground
D.) the equation in vertex form

PLEASE HELP ME :( I CAN'T ANSWER IT :(

Question

On earth, the height, h metres, of an object fired upward from the earth's surface at 48m/s is described by the equation h=48t-16t^2 where t seconds is the time since the object was fired upward.
Determine:
A.) the maximum height of the object
B.) the times at which the object is 32m above the ground
C.) the time at which the object hits the ground
D.) the equation in vertex form


PLEASE HELP ME :( I CAN'T ANSWER IT :(

isaidavila · Answer

Calculate how much tine it takes to reach the max height
Vf=Vo-gt
0=48-(9.8)t
48=9.8t
t=? 
Then replace t=?? In the function of height to find it

isaidavila · Answer

The time when it is 32m above is
h=48t-16t^2 then h=32
32=48t-16t^2 we can divide all by 16
--->2=3t-t^2 solving

anonymous · Answer

Why divide it to 16?

mathmale · Answer

Dividing the equation by 16 is not required, but does reduce the problem a bit.

caozeyuan · Answer

I feel like the max height is better don with differentiation

caozeyuan · Answer

since you are asked for a max value of a function, take first direvative and set to 0 find the t and plug bakc in

mathmale · Answer

Differentiation?  That depends upon whether alfers101 has taken calculus or not.  He may be in algebra.  Please ask about current course work before making a statement like that.

anonymous · Answer

I'm doing algebra

mathmale · Answer

OK.  To find the max height, find the vertex.

Know the formula for the horiz. coordinate of the vertex?   x=-b/(2a)