Inclined Plane 17/10

Forces acting on an object on an inclined plane

 

 

Mechanical Advantage

The mechanical advantage of a machine is the ratio of the load to the applied force. In other words, mechanical advantage determines how much force we need to perform a task. For example, the greater the mechanical advantage of a machine, the less force we need to have to perform a task such as moving an object. The opposite is true as well. Mathematically, mechanical advantage (MA) = load ÷ applied force. A good mechanical advantage is one that is greater than 1.

Inclined Plane

The purpose of an inclined plane as a simple machine is to move something from a lower height to a higher height with less effort. An object simply placed on a tilted surface often slides down the surface (see Figure 1) because of the force in the downhill direction. In other words, the forces in this scenario are unbalanced (i.e. there is no upward force to counteract the downward force and therefore, the object would slide down).The rate at which the object slides down is dependent upon how tilted the surface is; the greater the tilt of the surface, the faster the rate at which the object will slide down it. This is measured by the angle of inclination. Students can find this using a protractor. Friction also affects the movement of an object on a slope. Friction is a force that offers resistance to movement when one object is in contact with another. Imagine now that you were on the downside of the object and applying force to keep the object in the same place (not moving). To keep the object stationary, the force you would have to apply would need to equal the downward force due to gravity. That would be an example of balanced forces. If you wanted to push the force upwards, you would need to exceed the force of gravity.

A sketch of a cart on a ramp shows the angle of inclination, distance, height, force of gravity, pull force and friction.
Figure 1: This diagram shows how ancient cultures used inclined planes to move heavy stones to the top of their pyramids. The force of gravity, friction and the pull force all affect how easy (or hard) it is to pull the cart up the inclined plane.

To understand an object’s motion on an inclined plane, it is important to analyze the forces acting upon it. The force of gravity (also known as weight) acts in a downward direction. When the angle of inclination is greater, and the slope is steeper there is more weight component to overcome. With a shallower slope the weight component is easier to overcome and requires less effort.

The mechanical advantage of an inclined plane depends upon its slope and height. To find the mechanical advantage of an inclined plane, divide the length of the slope by its height.

Mechanical advantage of an inclined plane = length of slope ÷ height of plane

An inclined plane produces a mechanical advantage to decrease the amount of force needed to move an object to a certain height; it also increases the distance the object must move. The object moving up an inclined plane needs to move the entire length of the slope of the plane to move the distance of the height. For example, if you have a ramp with a slope length 20 meters that rises 5 meters high, then your trade-off is moving the 20 meters distance versus lifting straight up 5 meters, and your mechanical advantage is 4.

Screw

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Accelerators and liquids in cans

 

Accelerators and liquids in cans

 

4×4 competitions

 

 

Problem to solve: How to transport liquids in the container (can ) without spilling?

In small groups:

(1) discuss the different  ways you can secure the  can in your effort  to minimise the loss of liquid in the can (the load )

(2) design simple experiments you can do to  observe the movement of liquids in the clear plastic bottle at different speeds or angles

(3) do the experiments and write up your observations in your blog.

 

 

STAGE 5 STEM Drones

7 Feb  Tuesday

The role of Science in STEM and What drones are used for around the world.

Pages 29 to 33 National Sciene Week 2016 dronesdroidsandrobots2016v5

Legalities/safety for drone usage in Australia.  https://www.casa.gov.au/aircraft/landing-page/flying-drones-australia

Components of drones: Transmitter (Tx), receiver, Flight control board, Electronic Speed control, Electric Motor, Propeller.

Propeller and Newton’s third law:

Answer the Following Questions:

  1. What are the four forces that act on an aircraft/flying object?
  2. What are three things that determine the weight of an airplane/flying object?
  3. What are two things that determine the thrust of an airplane/flying object?
  4. A high thrust to weight ratio means that the aircraft will have high _____________and a high _______________.
  5. If the thrust to weight ratio is greater than 1, this means the aircraft/flying object will be able to ______________________________.
  6. Explain what a ratio is in your own words.
  7. Write a few sentences summarizing this activity and what you learned from it.

cub_airplanes_lesson10_activity1_worksheet

newton-law-thrust-drag-ratio

activity from :https://www.grc.nasa.gov/www/k-12/BGP/Sheri_Z/thrustwtrat_act.htm

https://www.grc.nasa.gov/www/k-12/airplane/newton3.html

https://www.grc.nasa.gov/www/k-12/BGA/Monroe/lift_theories_act.htm

 

 

other information

frisbee_physics

 

 

 

9STEM

Lesson 1: Introduction

CSIRO videos

Drones and tracking devices  (CSIRO Episodes) https://tenplay.com.au/channel-eleven/scope/season-3/episode-137

24 mins

 

Drones andAustralian laws:

https://www.choice.com.au/electronics-and-technology/gadgets/tech-gadgets/articles/drones-and-privacy-rights

Drones and personal surveillance

The legal view
New rules on the way
Drones and privacy rights
The current rules
The dos and don’ts
Small vs large drones
Playing nice with your drone

http://www.smh.com.au/federal-politics/political-news/drone-safety-review-called-by-turnbull-government-20161009-gry9x9.html

http://magazines.scholastic.com/news/2015/01/Invasion-of-the-Drones

https://www.rpastraining.com.au/casr-101-uav-drone-legal-or-illegal

http://www.environment.nsw.gov.au/policies/parks-drones-policy.htm

Lesson 3: Parts of drones

Learn about current and future uses of drones as well as arguments for and against the umanned flying vehicles.

http://www.robotshop.com/blog/en/make-uav-lesson-1-platform-rtf-arf-kit-custom-13989

Quiz:  http://knowbeforeyoufly.org/resources/are-you-ready-to-fly-a-drone/

http://knowbeforeyoufly.org/frequently-asked-questions/

download:  http://www.environment.nsw.gov.au/resources/parks/policies/parks-drone-use-160669.pdf

STEM

STEM  projects     (1) Colonisation of Mars  Stage 5

  1. Drones – exploration of the surface earth -possibility of drone carrying weights
  2. Plant chamber food for survival   – gravity   http://news.nationalgeographic.com/news/2012/121207-plants-grow-space-station-science/ 
  3. Plants chamber food for survival –LED Lights Used in Plant Growth Experiments for Deep Space Missionshttp://www.nasa.gov/centers/kennedy/home/plant_growth.html