Presentation on theme: " Is a wheel with a grooved rim in which a rope can run to change the direction of the pull (force) that lifts the load."— Presentation transcript:
Is a wheel with a grooved rim in which a rope can run to change the direction of the pull (force) that lifts the load.
Use the following steps: Clip a binder clip to the end of a half-meter stick. Lay the tick on your desk so that only the clip extends over the edge. Use a piece of duct tape, positioned close to the clip, to prevent the stick from sliding side to side. Put a heavy dictionary on the other end of the stick to hold it down.
Purpose: To investigate a different type of simple machine known as a pulley and identify how it makes work easier. Q?
Draw, explain, diagram all the pulleys you can make using the materials you have been given.
Has a wheel that is attached to something above the load.
Has a wheel that is attached to the load
What did you learn today? Did you answer your question? Were you able to include any new vocabulary?
One Pulley Systems Line of Learning (LOL) A pulley is a wheel with a grooved rim in which a rope can run to change the direction of the pull (force) that lifts the load. A fixed pulley has a wheel that is attached to something above the load. A movable pulley has a wheel attached to the load (moves with the load)
One Pulley Systems Line of Learning (LOL) Mechanical Advantage reduces the effort (force) needed to lift the load or overcome a resistance; it results from using a simple machine. Directional Advantage is a change in direction that results from passing a rope through a pulley
One Pulley Systems Line of Learning (LOL) Do single-pulley systems provide advantage? –Single-fixed pulley = directional advantage, they change the direction of effort needed –Single moveable pulley = mechanical advantage, they reduce the effort needed to lift the load
Purpose: To discover the advantages of using pulleys Q? Is there any advantage to using two pulleys at the same time? Why or Why not.
How can you build a pulley system using 2 pulleys? Use what you already know about pulley systems.
Can you build a system that changes the direction you are pulling?
Two Pulley Systems Line of Learning (LOL) Two pulley systems can provide a greater mechanical advantage when lifting a load that having one pulley A simple machine is any of the six basic devices that provide mechanical or other advantage like levers and pulley The 6 simple machines are –Screw-wheel and axle –Wedge- lever –Inclined plane- pulley
You will need to work in your groups and compete against the other tables to build pulleys. On your mark get set…..
Pulleys at Work!
Title: Effort in Pulley Systems Purpose: To investigate the relationship between the number of ropes pulling on the load and the effort it required to lift the load. Q? Is there a relationship between the number of ropes supporting the load and the effort required to lift the load?
Based on your data which pulley do you believe is giving you the most advantage? Why? How do the number of supporting ropes impact the advantage? What relationships can you see in this chart?
Effort in Pulley Systems Line of Learning (LOL) The greater the number of ropes supporting the load, the less effort needed to lift the load –More ropes = less effort The more supporting ropes you have the less work you have to do To figure out the effort you need divide the load by the number of supporting ropes. (Example on next slide)
If I had a load that was 30 N what would my effort be if I had…. 1 supporting rope = ________ 2 supporting ropes = ________ 3 supporting ropes = ________ 5 supporting ropes = ________ 6 supporting ropes = ________
Title: Measuring Distance Purpose: To record and compare the distance moved by the load and the effort in four pulley systems. Q? Is there hidden cost when we use simple machines, pulleys to lift a load? If so what do you think it is and why?
What are the advantages and disadvantages to using pulleys?
Measuring the Distance Line of Learning (LOL) “You never get something for nothing” applies to pulleys because….. The benefits gain (making work easier) by using simple machines are always balanced by cost. When the benefits outweigh the cost the machine is a useful tool. With pulleys we looked at the number or ropes compared to the distance required to travel….if you had to triple the distance the machine was not a useful tool