Grade 8 Mechanical Systems Topic 8: People and Machines

Grade 8 Mechanical Systems

Topic 8: People and Machines

People and Machines

The first cars were known as “horseless carriages”.

People and Machines

Canadians use lead-free gasoline because lead causes many health problems.

(Acute lead poisoning can cause blindness, brain damage, kidney disease, convulsions, cancer and death. Children exposed to low levels of lead poisoning have lower IQs, reading and learning disabilities, impaired hearing, reduced attention span, hyperactivity, behavioural problems and growth interference. Adults exposed to lead experience high blood pressure, hypertension, cardiovascular disease and death.)

People and Machines

Why did producers remove the chemical Freon 12 from refrigerators and car air conditioners?

It contributed to the destruction of the ozone layer.

NASA projections of protective ozone concentrations if CFCs like Freon 12 were not banned.

The Industrial Revolution

Society was transformed by the invention of the steam engine. Where before the steam engine, work was performed by hand labour, after the steam engine was built, steam-powered machinery could replace many workers. This led to mass production, the manufacturing of large quantities of a standardized item by standardized mechanical processes. The assembly line was born.

The Industrial Revolution

Assembly lines are designed with a sequential organization of workers, tools or machines, and parts in mind.

Ford assembly lines started in 1913.

Assembly Line

Which Came First?

“Did changes in society (our desire to meet our needs and wants) result in new technology, or did new technology change society?” That is a question that still remains unanswered.

Prior to the 1970s, people thought that fuel was unlimited and that cars were harmless to the environment.

“Land Yachts”

Which Came First?

In the 1970s, scientists began to inform people about a shortage of fuel and the negative environmental effects of fuel combustions. How did this affect people?

They changed their attitude and choice in vehicles.

1970 Mustang

1974 Mustang II

Which Came First?

Some alternatives to gasoline for vehicles are hydrogen fuel cells, solar power, battery power, electricity, vegetable oil

Hydrogen fuel cells produce electricity and drinkable water.

Solar-powered car

Which Came First?

Some alternatives to gasoline for vehicles are hydrogen fuel cells, solar power, electricity/ battery power, vegetable oil

The Pivo 2 from Nissan is a battery-powered car with wheels that can pivot 90 degrees and a driver's cabin that can spin around completely.

Which Came First?

Some alternatives to gasoline for vehicles are hydrogen fuel cells, solar power, electricity/ battery power, vegetable oil

What Is It For?

Scientists and technicians must always ask questions, evaluate their work, and decide if changes need to be made.

They often have to weigh the positive and negative effects of a technology or a new discovery.

Just because scientists can make something does not mean they should.

What Is It For?

What are the positives and negatives of using nuclear power to generate electricity?

What Is It For?

What are the positives and negatives of using nuclear power to generate electricity?

Positives: clean, little pollution, awareness of nuclear capabilities, lots of power

Negatives: huge risk of environmental disaster

What Is It For?

Nuclear power plant at Fukushima, Japan in 2011 after explosion and fire.

Chernobyl Birth Defects

The Ukraine reactor explosion in 1986 sent radioactive material into the atmosphere.

Birth defects were common in the areas most affected.

Think About It

Other than price tags, costs can also apply to other things, such as the cost to society or the environment.

Besides the impact of a product while it is in use, consider how a product is made and what becomes of it when it is discarded. Do we need it or do we want it?

Designed for Comfort

Why do you think that comfort is a key factor in designing new technology?

People usually want to buy comfortable items.

While both chairs can perform the same task, the more comfortable one is preferred.

The Science of Comfort

When ergonomic researchers discover something that increases the comfort or efficiency of a particular item, technicians are quick to build, test, and market the changes.

Review

What is the first step when designing a new machine or redesigning an existing machine? (What is the first question you must ask yourself about the machine you want to build?)

What is its purpose?

What Is Its Purpose?

What is the purpose of the invention shown below?

What Is Its Purpose?

It was patented in 1913 by Jacob Everette Dodd of Yoakum, Texas.

The “Baby Protector” was created to prevent babies from putting dangerous things into their mouths.

Review

The relationship between science and technology is often called the “chicken and egg” argument (Which came first, the chicken or the egg?). Explain how science and technology are like the chicken and the egg.

Chicken and Egg Argument

Where do eggs come from?

Chickens

Where do chickens come from?

Eggs

Review

The relationship between science and technology is often called the “chicken and egg” argument (Which came first, the chicken or the egg?). Explain how science and technology are like the chicken and the egg.

• Science and technology are linked together.

• One leads to another… which one led to the other?