Acceleration and Moving Objects

[Soaring Crane]

A large boulder is ejected vertically upward from a volcano with an initial speed of 40.1 m/s. (Air resistance can be ignored.)

a) At what time after being ejected is the boulder moving at 19.2 m/s upward? (g = 9.80 m/s^2)
b) At what time is it moving at 19.2 m/s downward? (g = 9.80 m/s^2)
c) When is the displacement of the boulder from its initial position zero? g = 9.80 m/s^2
d) When is the velocity of the boulder zero? g = 9.80 m/s^2

I did and understand these four parts. Now the following two parts are the ones I do not understand.


e) What is the magnitude of the acceleration while the boulder is moving? (Take g = 9.80 m/s^2 for free fall acceleration)

Well, the boulder can move up or down, but is the magnitude 9.80 m/s^2 for both scenarios?

f. What is the direction, up or down, of the acceleration while the boulder is moving?

Won't the direction be down?

Thanks for any help.

 

[Kurdt]

Yep you have that question licked it seems.

 

[Gablar16]

Let me try to help. For (a) I think you need something similar to V=Vo+at