Answer:
The value of the average convection coefficient is 20 W/Km².
Explanation:
Given that,
For first object,
Characteristic length = 0.5 m
Surface temperature = 400 K
Atmospheric temperature = 300 K
Velocity = 25 m/s
Air velocity = 5 m/s
Characteristic length of second object = 2.5 m
We have same shape and density of both objects so the reynold number will be same,
We need to calculate the value of the average convection coefficient
Using formula of reynold number for both objects



Here, 


Put the value into the formula


Hence, The value of the average convection coefficient is 20 W/Km².
(a) The angular acceleration of the wheel is given by

where

and

are the initial and final angular speed of the wheel, and t the time.
In our problem, the initial angular speed is zero (the wheel starts from rest), so the angular acceleration is

(b) The wheel is moving by uniformly rotational accelerated motion, so the angle it covered after a time t is given by

where

is the initial angular speed. So, the angle covered after a time t=3.07 s is
Hello! B. would be an example of a chemical change.
Answer:
C. Converting Energy
Explanation:
Hope this helped, Have a Wonderful Day!!
For an object moving in a path that's a circle or a part of one,
the centripetal force acts in the direction toward the center of
the circle. That direction is perpendicular to the way the object
is moving.