Answer:
From question (a) and (b) the pendulum motion is perpendicular to the force so the normal force will do no work and the tension in the string of the pendulum will not work

And
so

c
An example will be a where a stone is attached to the end of a string and is made to move in a circular motion while keeping the other end of the string in a fixed position
d
A dog walking along a surface which has friction, here the frictional force would acting in the direction of the motion and this would do positive work
Explanation:
Answer:
1.89mol
Explanation:
The entropy change during free expansion is express as

Where S is the entropy of the system,
n is the amount of mole
R is the gas constant = 8.314 and
V is the volume occupied at the initial and final stage
since the process is n adiabatic free expansion, the entropy of the system is constant. Hence we can re-write the equation as

where the
and 
and
Now if we substitute in values we arrive at

Answer:
The answer is C she didn't mark C so its your best best of trying.Good Luck!
Answer:
A)t=<u>1.375s</u>
B)t=11s
Explanation:
for this problem we will assume that the east is positive while the west is negative, what we must do is find the relative speed between the wave and the powerboat, and then with the distance find the time for each case
ecuations
V=Vw-Vp (1)
V= relative speed
Vw= speed of wave
Vp=Speesd
t=X/V(2)
t=time
x=distance=44m
A) the powerboat moves to west
V=18-(-14)=32m/s
t=44/32=<u>1.375s</u>
B)the powerboat moves to east
V=18-14=4
t=44/4=<u>11s</u>