College Physics falling object?

Question

A ball is thrown vertically upward with a speed of +12.0 m/s.

(a) How high does it rise?

_____ m (By the way the answer is not 4)

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

____s

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

____s

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

_____m/s

Thanks for any help!!!

Answer 1

a) 7.35 m above the throwers hand when they let go

b) 1.22 sec

c) you have to know the initial height above the ground to answer it

d) -12 m/s

Answer 2

V1 = 12 m/s

V2 = 0

a = -9.8 m/s

d = ?

V2^2 = V1^2 + 2ad

0^2 = 12^2 + 2(-9.8)d

0 = 144 - 19.6d

19.6d = 144

d = 7.35 m

(b) V2 = V1 + at

0 = 12 + (-9.8)t

12 = 9.8t

1.2245 = t

(c) t = 2*1.2245 = 2.449 s

(d)  d = 0

      V1 = 12

        a = -9.8

      V2 = ?

        

      V2^2 = V1^2 + 2ad

       V2^2 = 12^2 + 2(-9.8)(0)

       V2^2 = 12^2

        V2^2 = 144

        V2 = +-12

   Since it's returning the sign must be negative.  V2 = -12 m/s