Answer:
The force acting on the ball is 92.4 N.
Explanation:
Given that,
Initial speed of the ball, u = 0
Final speed of the ball, v = 31.6 m/s
The average power generated during the serve is 2920 W. Power generated by an object is given by :

W is the work done, W = Fd

Since, 
So,

F is the force acting on the ball

So, the force acting on the ball is 92.4 N. Hence, this is the required solution.
Answer:
v=20m/S
p=-37.5kPa
Explanation:
Hello! This exercise should be resolved in the next two steps
1. Using the continuity equation that indicates that the flow entering the nozzle must be the same as the output, remember that the flow equation consists in multiplying the area by the speed
Q=VA
for he exitt
Q=flow=5m^3/s
A=area=0.25m^2
V=Speed
solving for V

velocity at the exit=20m/s
for entry

2.
To find the pressure we use the Bernoulli equation that states that the flow energy is conserved.

where
P=presure
α=9.810KN/m^3 specific weight for water
V=speed
g=gravity
solving for P1

the pressure at exit is -37.5kPa
A jagged line represents a resistor .
Answer:
The potential difference is 121.069 V
Solution:
As per the question:
Diameter of the cylinder, d = 9.0 cm = 0.09 m
Length of the cylinder, l = 40 cm = 1.4 m
Average Resistivity, 
Current, I = 100 mA = 0.1 A
Now,
To calculate the potential difference between the hands:
Cross- sectional Area of the Cylinder, A = 
Resistivity is given by:



Now, using Ohm's Law:
V = IR
