Physics Help! Kinematic Equations?

Question

I did these problems already, but I would like to check them. If you could let me know what you get so I can see if I'm doing them right or not.

1.) A bus slows down uniformly from 21 m/s to 0 m/s in 21s. How far does it travel before stopping?

2.) A worker drops a wrench from the top of a tower 80.0m tall. What is the velocity when the wrench strikes the ground?

Thanks

Answer 1

For 1
v(t)=21-a*21
when v=0, the bus stops
so a=1
the displacement is
x(t)=21*t-.5*1*t^2
since t=21
x(21)=.5*21^2
220.5 meters

2) y(t)=80-.5*g*t^2
using g=9.81
when the wrench strikes the ground, y(t)=0
t=sqrt(160/9.81)

for speed
v=g*t
=sqrt(9.81*160)
39.6 m/s downward
j

Answer 2

1) 10.5m, 21/2 = 10.5 ( average speed over the bus' stop
2) 39.62817746 m/s ((.5(-9.81)t^2)+80=0 when T = 4.0385502 seconds. T(9.81) = Final velocity = 39.618