ans: a) -2.0m/s^2
b) 33.75m
-List our knows and unknowns:
vi=12.0m/s
vf=3.0m/s
t=4.5s
a=?
d=?
-a) solve for a. let’s choose a formula, avoiding d, as we do not want two unknown variables when solving for one. Here’s a good one:
vf=vi+at
-Plug in your values:
3.0=12.0+a(4.5)
-9.0=4.5a
-9/4.5=a
a=-2.0m/s^2
-b) solve for d. let’s choose a formula. Here’s a good one:
d=vit + 1/2at^2
-plug in your values:
d=(12.0)(4.5)+1/2(-2.0)(4.5^2)
d=(54)+(-20.25)
d=33.75m
