Answer:B,C,D
Explanation:
Thermodynamic efficiency is given by

efficiency can be increased by Keeping
constant and increasing 
Keeping
constant and decreasing
by increasing 
by decreasing
ratio
(C)
Explanation:
The circle has a radius r = 0.5 m, which means that its circumference C is

One revolution means that the stopper travels a distance equal to the circumference of the circle so the velocity of the stopper is

Answer:

Explanation:
The acceleration of an object is given by:

where
v is the final velocity
u is the initial velocity
t is the time interval it takes for the velocity to change from u to v
For the rocket in this problem,
u = 20,000 m/s
v = 24,000 m/s
t = 55.0 - 5.0 = 50.0 s
Substituting,

Assuming the friction between the skaters and the ice is negligible, the magnitude of Porsha's acceleration is 2.8m/s².
Missing part of the question: determine the magnitude of Porsha's acceleration.
Given the data in the question;
- Mass of Porsha;

- Mass of Zorn;

- Force of Porsha push;

Magnitude of Porsha's acceleration; 
To determine the magnitude of Porsha's acceleration, we use Newton's second laws of motion:

Where m is the mass of the object and a is the acceleration.
We substitute the mass of Porsha and the force he used into the equation
Therefore, assuming the friction between the skaters and the ice is negligible, the magnitude of Porsha's acceleration is 2.8m/s².
Learn more: brainly.com/question/25125444
Answer:
I don't really know but i have an idea
Explanation:
so acceleration means: increase in the rate or speed of something.
so just a head start.
your welcome!!