grd 8 science systems unit review

1. what are systems and types of systems

systems are groups of components working together to achieve a specific task. types of systems include physical (e.g. cars, lawnmower, air fryer), social systems (e.g. families, ant colonies, education system, laws). subsystems are smaller systems within a bigger system that contributes to the outcome (e.g. braking system in cars, ram in computers)

2. law of conservation of energy

the law of conservation of energy states that energy cannot be created or destroyed, but can be converted from one form of energy to another (e.g. chemical → thermal energy (burning wood)).

3. inputs, outputs, processing, and feedback systems

inputs = the energy, force, or raw materials that go into a system

outputs = the things or services the system produces based on the inputs and process

process = the actions taken by the system, converting the input into an output

feedback systems = uses output results to determine what changes with the input need to be made to have a different outcome

4. system components - simple machines

• subsystems can also be divided into mechanisms. a mechanism changes one type of force or action into another, force is any push or pull motion.

• simple machines include wheel and axles, wedges, inclined planes, screws, levers, and pulleys → these make it easier to lift or move things

• compound machines consists of 2+ of these simple machines

5. efficiency

• efficiency is the ability to do a task without wasting energy, effort, or raw materials.

• energy dissipation is when energy is lost from a system (e.g. leaky faucets, bouncing balls)

• energy cannot vanish or be destroyed, but can be “lost” as it converts from one form to another

• in mechanical systems, energy is most often lost as parts of a system warm up due to friction

6. automating

automation allows manufacturing, production, etc with minimal human assistance

• pros: allows workers to have better job positions, improves worker safety, no human errors in manufacturing, removes factory hazards

• cons: some fear that it will replace them for their job position, expensive factory equipment, people worry about cost of maintenance and repairs

7. energy in systems and the 5 main features for systems

• energy is the ability to do work (moving something against a force)

• 5 main features are purpose, inputs, process, outputs, components

8. industry and order of system unit parts

• an industry is a combination of systems working together to produce goods and services

• there are alternatives ways of meeting needs that are currently met by existing systems

• order = industry, systems, subsystems, components, mechanisms

9. long answer - give an example of a new tech that replaced an older system, explain why the new systems better. then give another example of an old tech that slowly got replaced by something newer

• one example of an old technology that got replaced by a newer one is the internal combustion engine that replaced the steam engine. the steam engine was important in early technology, being used for trains and ships. but, it required a lot of water and fuel, took long to heat up, was big, heavy, and hard to maintain. nowadays, we use internal combustion engines because it is much more smaller, lighter, efficient, and faster to start.

• another example of an old technology that slowly got replaced by newer tech is the landline telephone. landline telephones were used for many decades, being the main communication system in homes, but now, they have been replaced by smartphones that have more features. smartphones allowed people to text, video call, access to internet, photography, etc. in the end, landline telephones became uncommon, showing how newer systems often replace older ones, especially when they offer greater efficiency and usefulness.

10. math part.. - mass and weight, force of gravity formula, work formula, mechanical advantage

• mass is the amount of matter in an object, and is measured in kg. weight is the amount of force of an object due to gravity, measured in newtons (N)

• force of gravity (fg) = mass X strength of gravitational field, fg = mg (each 1.0kg has a weight of 9.8, basically, the strength of gravitational field is 9.8N pet kg)

• work (w) = force X distance (work is measured by joules (J), force is in newtons (N), distance is in metres)

• mechanical advantage (ma) = force of the object divided by force of the object with a simple machine