Answer:
a) 323.4J
b) 0J
c) -323.4J
Explanation:
a) W=Fd
F=ma
solve for acc. using kinematics
v^2=vo^2+2a(x)
8.41=2a(12)
4.205=a(12)
0.35=a
F=(77)(0.35)
F=26.95N
W=26.95*12...... W=323.4J
b) No acceleration, thus no force, thus no work!
c) W=Fd
F=ma
find acc. using kinematics: v^2=vo^2+2a(x)
0=(2.9^2)+2a(12)
0=8.41+2a(12)
-8.41=2a(12)
-4.205=a(12)
-0.35=a
F=(77)(-0.35)
F=-26.95N
W=(-26.95)(12)
W=-323.4J
Yes, work can be negative!