Final Review Powerpoint

Transcription

1 Final Review Powerpoint

2 Simple Machines- A device that makes work easier, faster, or changes the direction of force using few or no moving parts Rube Goldberg- a complex machine that does a simple task Wheel and Axle- a large circular object attached to a smaller circular object that turns. When rotated, it can reduce friction of heavy objects. A machine can: make work easier, faster, or more effcient

3 Lever A rigid bar used to turn about a fixed point called a fulcrum.

4 Parts of a Lever If the fulcrum is located at the turning point -The effort force is exerted on one arm (push or pull) - The load is the opposing weight which tends to move in the opposite direction as the effort Load Fulcrum Lever Arm Effort

5 Wheel & Axle The wheel and axle is a first class lever. The fulcrum is replaced with an axle (a rod) Lever arms are repeated around the axle. Rotates the full 360 degrees rather than teeter totter

6 How does it make work easier? It can either: Reduce the amount of force needed to move a distance Or Increase the distance the object moves (requires more force) Depending on where the effort is located: the axle or the wheel. Examples:

7 Pulleys A grooved wheel that rotates a rope, belt, or chain securely around it. It makes work easier by: changing the direction of force Reducing the effort applied.

8 Examples of Pulleys

9 Inclined Plane At an angle flat surface An inclined plane is any slanted surface used to raise a load from a lower level to a higher level. How does it make work easier? Allows heavy objects to be lifted with less effort (trade off: it moves a longer distance)

10 Examples of Inclined Planes Not a simple machine (the mountain)

11 Screw An inclined plane wrapped around a cylinder, forming threads (a path and pitch) Pitch is the distance between two threads Screws turn rotary motion into linear motion

12 Examples of Screws A screw can either: raise/move weight Press/ fasten objects together

13 A Wedge is a moving inclined plane -can be double sided (axe) or -single sided (door wedge) Tapers to a thin edge and is used for: -Splitting things (pushing them apart) -Tighten or hold things Wedge -Help grip things (space for fingers)

14 Examples of Wedges Almost all cutting tools make use of the wedge.

15 Work Work is done when a force moves an object a distance. Work = Force x Distance or W=FD Which example below is doing work? Remember, if it doesn t move, no work is done.

16 Therefore, energy is defined as The Ability to do Work

17 Kinetic Energy Energy of a moving object

18 Potential Energy The energy present in matter due to its position or condition Electrical Elastic Gravitational Thermal Chemical

19 Law of Conservation of Energy With every transformation, some energy is converted to less useful forms. Energy conversions are not 100% efficient. The energy output for the intended purpose is never the same as the energy we put in. 100 J electricity in 95 J heat out 5 J light out

20 What is Work? Work- the result of a force moving an object Work= Force x Distance What is Force? What is Distance? Force- A push or pull on an object that causes it to move, change a direction, or stop Distance- The amount of area an object will move

21 Moving Forward

22 Wait

23 Going In Reverse

24 What is Robotics (and a Robot)? Robotics involves the design, construction, and operation of a robot. A robot is a mechanical or virtual machine guided by a computer program that performs tasks that are simple or complex Can be controlled by a human or computer (autonomous)

25 What Robots Can Do Precision work Repetitive/monotonous work Dangerous work Exploration Education Competition Unmanned combat aerial vehicles must do precise, repetitive and dangerous work.

26 The most basic type of gear is called a simple gear train A simple gear train is two or more interlocking gears that transfer motion from one gear to the next. Though we are only going to look at two gears at one time, you can add on as many gears that you need.

27 A simple gear train can: Change direction of rotation Change speed A= Motor Gear (input) B= Wheel Gear (output) A B

28 A simple gear train can: Change direction of rotation Change speed Which one spins faster? A B Can anyone guess why this is?