The answer would be center of mass, B
Answer:
Speed = 3 [km/h]
Explanation:
To solve this problem we must use the definition of speed which relates the distance traveled for a while.
Distance = 1.5 [km] = 1500 [m].
time = 0.5 [hr] = 1800 [s]
Speed = Distance/time
Speed = 1.5/0.5
Speed = 3 [km/h] or 1500/1800 = 0.8333[m/s]
Explanation:
Equation for energy balance will be as follows.


Hence, 
Therefore, we will calculate the final temperature as follows.

= 868.03 R
Now, we will calculate the mass as follows.
m = 
= 
= 1.031 lbm
Hence,

Putting the values into the above equation as follows.


= 655.2 Btu
Thus, we can conclude that work done by paddle wheel is 655.2 Btu.