Please help with calculus, ill medal :))
what is the speed of the ball when it its the ground?
D(t) = -t^2+8t+1. d(t) is the height . The maximum height of the ball is17. What is the speed of the ball when it hits the ground, ?
time at which ball hits the ground is 8.12 s.

Question

Please help with calculus, ill medal :))
what is the speed of the ball when it its the ground?
D(t) = -t^2+8t+1. d(t) is the height . The maximum height of the ball is17. What is the  speed of the ball when it hits the ground, ?
time at which ball hits the ground is 8.12 s.

babykainui · Answer

Hello

roseliberty · Answer

Hi

babykainui · Answer

Please notice your equation is of the form $$d(t) = -g t^2+v_0t+h_0$$

roseliberty · Answer

i tried to substitute it into quadratic formula, which is recommended for this type of problem.

babykainui · Answer

You can apply the quadratic formula to find the time t

roseliberty · Answer

i calculated the time is 8.125

roseliberty · Answer

from the quadratic formula

jdoe0001 · Answer

well, first off, doesn't look like calculus
and the ball hits the ground when the y-value is 0, thus, set D(t) to 0
and solve for "x", or get the x-intercepts
|dw:1458343489474:dw|

$\bf D(t)=-t^2+8t+1\implies {\color{brown}{  0}}=-t^2+8t+1$

daniel.ohearn1 · Answer

Did you try deriving the equation yet?