Answer:
<em>The velocity of the ball as it hit the ground = 19.799 m/s</em>
Explanation:
Velocity: Velocity of a body can be defined as the rate of change of displacement of the body. The S.I unit of velocity is m/s. velocity is expressed in one of newtons equation of motion, and is given below.
v² = u² + 2gs.......................... Equation 1
Where v = the final velocity of the ball, g = acceleration due to gravity, s = the height of the ball
<em>Given: s = 20 m, u = 0 m/s</em>
<em>Constant: g = 9.8 m/s²</em>
<em>Substituting these values into equation 1,</em>
<em>v² = 0 + 2×9.8×20</em>
<em>v² = 392</em>
<em>v = √392</em>
<em>v = 19.799 m/s.</em>
<em>Therefore the velocity of the ball as it hit the ground = 19.799 m/s</em>
<h3><u>Answer and explanation;</u></h3>
Reflection;
- Bounces back from an opaque material
- Bounces back from the boundary of two mediums
- Seen in mirrors
Refraction;
- Passes through a prism
- Moves from one medium to another
- Seen in lenses
Reflection refers to the bouncing of waves such as light waves. It involves a change in direction of waves when they bounce off a barrier.
Refraction is the bending of waves when they move from one medium to another. It involves a change in the direction of waves as they pass from one medium to another.
Answer:
8563732.58906 Pa
3992793.23326 Pa
5708.00923 J
Explanation:
V = Volume
N = Number of molecules = 
T = Temperature = 300 K
b = 
= Boltzmann constant = 
P = Pressure
We have the equation

The pressure is 8563732.58906 Pa
For isothermal expansion

The pressure is 3992793.23326 Pa
Work done is given by

The work done is 5708.00923 J
Complete Question
A certain refrigerator, operating between temperatures of -8.00°C and +23.2°C, can be approximated as a Carnot refrigerator.
What is the refrigerator's coefficient of performance? COP
(b) What If? What would be the coefficient of performance if the refrigerator (operating between the same temperatures) was instead used as a heat pump? COP
Answer:
a

b
Explanation:
From the question we are told that
The lower operation temperature of refrigerator is
The upper operation temperature of the refrigerator is 
Generally the refrigerators coefficient of performance is mathematically represented as

=> 
=> 
Generally if a refrigerator (operating between the same temperatures) was instead used as a heat pump , the coefficient of performance is mathematically represented as
=>
=>
What work??? I don’t see anything