Download Chapter 10 You are driving down the highway at 55mph with your

Chapter 10
1. You are driving down the highway at 55mph with your foot out the
window. If your foot has a cross sectional area of 0.3ft2 with a drag
coefficient of 1.17, what force is the air pushing on your foot with?
2. How many times more drag force is there on a car traveling at 70mph
compared to 50mph?
3. An electronic flow sensor has a sensitivity of 100mV/gpm. What is its
output when measuring a flow of 25gpm?
4. Some electronic equipment is cooled by passing air through it with a
fan. If air is flowing through an opening with an area of 3.0cm2 at a
velocity of 15cm/s, what is the flow rate?
5. Water is flowing through a large section of pipe at a rate of 15in3/s.
The pipe then narrows to a cross sectional area of 5in2. What is the
velocity of the water in the narrow section of pipe?
6. You are playing in the backyard trying to squirt your brother with the
water hose. You place your thumb over the end of the hose resulting
in the water squirting farther. By placing your thumb over the hose
you have decreased the area through which the water flows by four
times. How many times faster does the water flow out the end of the
hose than in it?
7. Very high power electrical equipment is sometimes cooled with water.
Water is pumped through a water jacket thermally connected to the
equipment transferring the heat out. If the flow rate is 50gpm at a
pressure of 30psi, what horsepower pump is needed?
8. If a 3hp fluid pump is operating at 60psi, what is the flow rate out of
it?
9. In the absence of friction if a fluid is flowing through a pipe and the
pipe narrows and the speed of the fluid increases so that its kinetic
energy doubles, how many times does the fluids energy from pressure
change?
10. A windmill used to create electrical power, can be made from a slot
car motor connected to some type of device to catch the wind. As the
motor spins it will generate a voltage, i.e. it will act as a generator. If
the effective area of air the windmill catches is 0.4m2, and the wind is
blowing at 5.0m/s, what power can the windmill generate? Assume
the generator is 100% efficient.
11. A hydroelectric generator can be made from a slot car motor
connected to a turbine placed in flowing water. As the motor spins it
will generate a voltage, i.e. it will act as a generator. If the effective
area of the turbine is 0.2m2, and the water is flowing at 4.0m/s, what
power can the windmill generate? Assume the generator is 100%
efficient.
12. Using table 10.1 what shape has the lowest drag coefficient?
13. If 10gpm is flowing into a volumetric flow meter, what volume does
it measure after 20minutes?
14. How does a thermal flow sensor work?
15. In a series electrical circuit the current is the same everywhere.
Likewise the flow of a fluid through a set of pipes in series will be the
same regardless of any changes in diameter of the pipes. If the flow at
one point in a set of pipes in series is 4gpm, what is the flow at any
other point?
16. A squirrel cage blower mounted on the back of a piece of electronic
equipment is blowing air at a rate of 22cfm, that is 22ft3/min. What is
this rate in cm3/min?
17.If a 5hp pump delivers a pressure of 100psi, how many gallons per
minute is it pumping?
18. Why does the shower current move toward you while taking a
shower?
19.How much more power is there in a wind traveling a 20m/s compared
to 10m/s?
20. A toilet has the unit lpf written on top of it. What does this stand for?