# A ball is tossed...

• Oct 11th 2009, 04:28 PM
mathcalculushelp
A ball is tossed...
A ball is tossed straight up into the air from a bridge,and its height above the ground t seconds after it is thrown is

f(t)=-16t^2 + 108t + 82 feet.

a.How high above the ground is the bridge?

b. Write a function A(b) that gives the average velocity of the ball from t=0 to t=b seconds.Use the function to calculate the average velocity of the ball the first two seconds it is in the air.
• Oct 11th 2009, 04:32 PM
pickslides
Quote:

Originally Posted by mathcalculushelp
A ball is tossed straight up into the air from a bridge,and its height above the ground t seconds after it is thrown is

f(t)=-16t^2 + 108t + 82 feet.

a.How high above the ground is the bridge?

Find \$\displaystyle f(0)\$
• Oct 11th 2009, 04:39 PM
Arturo_026
for b)

A(b) = (f(0) - f(b)) / (0 - b)

plug values and simplify
• Oct 11th 2009, 04:50 PM
mathcalculushelp
Help me find t...?
-16t^2 + 180t + 48...??

I am getting stuck at finding t.

Iam not able to get the factors.If I use -b_+sq rt b^2 -4ac/2a then I get complicated ans.

How should I find t?
• Oct 11th 2009, 04:53 PM
Arturo_026
I think you need to find f(0) not f(t)=0

-16(0)^2 + 180(0) + 48 = f(0) , that's how high the ball is