I have a few problems I'm having trouble with. If I can get some help with this one I should be able to figure out the rest I have. 1. A rock is thrown downward from the top of a tower with an initial speed of 12 m/s. If the rock hits the ground after 2.0 s, what is the height of the tower? (neglect air resistance). Known: [tex]Vi=12m/s[/tex] [tex]\Delta t=2 s[/tex] [tex]a=9.8 m/s[/tex] Relevant equations: [tex]Vf^2=Vi^2+2a(\Delta y)[/tex] My attempt: [tex]\Delta y=Vf^2-Vi^2-(2a)[/tex] [tex]\Delta y=0-144-(2*9.8 m/s^2)[/tex] [tex]\Delta y=-163.6[/tex] [tex]Height=163.6 m[/tex] I'm not sure if this is right. I think I run into trouble when I rearrange the formula. Multiple choice answer D is 63 m, so it's either a typo or I'm doing something wrong. A little guidance please? Thank you!