Checking kinematics answers: acceleration, projectile motion, and free fall

[honestliar]

Homework Statement

An object starts from rest w/ a constant acceleration of 8m/s^2 along straight line.
a)find the speed at the end of 5 sec.------40sec
b)the ave. spped for the sec interval------20m/s

A stone is thrown vertically upward w/ an initial velocity of 49m/s
a)How long does it take to reach the highest point-----5 sec
b)How far does the stone go---122.5m
c)How fast does the stone go----4.52s



A stone is dropped from a bridge w/c is 60m above seal level. a)find the time before it hits the water----12.24s
b)Speed upon hitting the water---34.29m/s


thanks

 

[tiny-tim]

Hi honestliar!

They're ok except for …

a)find the time before it hits the water----12.24ss

(and I don't understand the question "c)How fast does the stone go" )