Thursday

September 3, 2015
Posted by **Tierney** on Thursday, September 30, 2010 at 4:48pm.

(a) How high does the ball rise?

- physics -
**bobpursley**, Thursday, September 30, 2010 at 6:11pmfind time of flight:

hf=ho+Vi*t-4.9t^2

solve for t.

Then solve for height at t/2

- physics -
**Henry**, Thursday, September 30, 2010 at 7:19pmd(up) = Vo*t + 0.5at^2,

v=at,

a = v/t,

Substitute v/t for a in the 1st Eq:

d(up) = Vo*t + 0.5(v/t)t^2,

d(up) = 19.5t + 0.5 * (19.5)t,

d(down) = 0.5 * 9.8t^2,

d(up) = d(down),

19.5t + 9.75t = 4.9t^2

Solve for t:

29.25t = 4.9t^2,

4.9t^2 - 29.25t = 0,

Factor out t:

t(4.9t - 29.25) = 0,

t = 0,

4.9t - 29.25 = 0,

4.9t = 29.25,

t = 5.97 s.

Solution set: t = 0, and t = 5.97 s.

Select t = 5.97 s.

d(up) = 19.5 m/s * 5.97 s + 9.75 m/s * 5.97 s = 174.6 m.

- physics -
**Ramsha**, Saturday, November 19, 2011 at 4:15amSI unit of delta V/ delta t and dV/dt