A ball is thrown vertically upward with a velocity of +13.0 m/s?

Question

A ball is thrown vertically upward with a velocity of +13.0 m/s.

(a) How high does it rise?

(b) How long does it take to reach its highest point?

(c) How long does the ball take to hit the ground after it reaches its highest point?

(d) What is its velocity when it returns to the level from which it started?

Answer 1

(a.) Ignoring air resistance:
s = s(zero) + v(zero)t + (1/2)at^2
v(zero) + at = 0
v(zero) = -at
13 = 9.8t
t = 1.32653sec [<----- this is part (b.)]

s = (1/2)at^2
s = (1/2)(9.8)(1.32653)^2
s = 8.6224m

(c.)
s = s(zero) + v(zero)t + (1/2)at^2
13t -4.9t^2 = 0
t(13 - 4.9) = 0
t = 0 ; 4.9t = 13
t = 2.6531sec.

(d.) By symmetry: v(final) = 13m/s