Midterm Study Guide

   Questions

Advantages of Pneumatics over Hydraulics– (write/type the 5 key things from the flashcards here)

Any equipment employing pneumatics uses an ________ set of components: a pneumatic circuit consisting of active components such as gas compressor, transition lines, air tanks, hoses, open atmosphere, and passive components.

Interconnecting

Hydraulics present certain advantages over pneumatics, but in a given application, pneumatic powered equipment is more suitable, particularly in industries where the factory units are plumbed for _____________ air.

compressed

In order to affect ______ motion, pneumatics employs compression of gases, based on the working principles of fluid dynamics in the concept of pressure.

Mechanical

Hydraulics means use of __________ fluids to execute a mechanical task.

Pressurized

Commonly seen _________ based equipment types are hydraulic presses, hydraulic hoppers, hydraulic cylinders, and hydraulic rams.

hydraulics

2.       Chapter 18 -  (write/type 3 key things from the flashcards here)

Which technologies apply the concepts of Newton's third law?

jet airplanes, fireworks, and recoil gun

What is Newton's Third Law? Use it to explain how a rocket engine propels a spacecraft into outer space.

Every action has an equal and opposite reaction. Thrusters will propel the spacecraft into outer space by pushing hot gases out a very high velocity. According to Newton's third law, the spacecraft will experience an equal and opposite force, propelling it upward into space. Also, acceleration of the games times their mass equals the acceleration of the rocket times its mass.

What is meant by the term "resistance"?

Resistance opposes forward movement.

3.       Chapter 19 -  (write/type 5 key things from the flashcards here)

Other engineers have tackled the problem of making more efficient cars. What are some new car technologies in development today that are designed to reduce the use of fossil fuels?

Hybrid vehicles have both gas engines, and electric motors and batteries, so they can use both energy sources, either one at a time or together. Hybrid vehicles capture energy from braking to generate electricity and charge the batteries. Solar - powered vehicles use photovoltaic (solar) cells; hydrogen-powered vehicles are reenergized with hydrogen gas, or are powered by fuel cells.

Give both an advantage and a disadvantage of a diesel engine over a gasoline engine.

Diesel engines are more powerful, and therefore are used to power trains, cargo ships, and other heavy vehicles. Diesel engine exhaust contains more soot and other particulate pollutants than gasoline engines

What is the difference between a gas engine and diesel engine?

The main difference between the two types of engines is in the way that they ignite the gas-air mixture. Gasoline engines take in a mixture of gas and air, compress it, and then ignite it with a spark plug. Diesel engines take in just air, compress it, and then inject fuel into the compressed air. The air is compressed enough to raise its temperature sufficiently so that the injected fuel will ignite it.

What information would you need to know to determine the force with which the piston pushes the air during the second step of the diesel cycle?

P=F/A, therefore F= A x P. You would need to determine the pressure in the chamber and the surface area of the piston.

What is the relationship between volume, temperature, and pressure that is useful for designing engines?

Volume, temperature, and pressure are related by the equation "Pressure (P) is proportional to the temperature (T) of the gas, divided by the volume (V) of the chamber.

4.       

      Inside the Teenage Brain – (write 3 key facts)

What is one of the enduring lessons for parents in the video?

Even though the public perception is about building bigger and better brains, what the research shows is that it's the relationships, it's the connections, it's the people in children's lives who make the biggest difference."

What effect do sleep debts have on the brain?

Some say these sleep debts can have a powerful effect on a teen's ability to learn and retain new material -- especially abstract concepts like physics, math, and calculus.

How does lack of sleep affect the teenage brain?

Sleep affects memory and learning

5.       

       Chapter 20 (write/type 5 key things from the flashcards here)

Why is the Stirling engine considered a closed system?

Because the working fluid remains inside the engine. Only energy crosses the system boundary.

What were the design requirements for the wheelchair engine? Why did the Stirling engine seem like it might meet the criteria?

The engine had to be quiet and had to deliver a lot of power. Because the Stirling engine is an external combustion engine, there are no explosions inside of the combustion chamber. Therefore, the engine is very quiet.

In a Stirling engine, the working gas never leaves the engine. How is this different than a combustion engine?

A combustion engine is an open pneumatic system - air and fuel vapor enter the chamber on every cycle, are burnt, then are forced out into the open air.

Why is the Stirling engine considered a closed system?

Because the working fluid remains inside the engine. Only energy crosses the system boundary.

What were the design requirements for the wheelchair engine? Why did the Stirling engine seem like it might meet the criteria?

The engine had to be quiet and had to deliver a lot of power. Because the Stirling engine is an external combustion engine, there are no explosions inside of the combustion chamber. Therefore, the engine is very quiet.