1 Machines and Mechanical Systems

2 How were the great pyramids built? How can giant buildings be made from objects too heavy to carry? Up until relatively recently, we could only go so high. After a certain point, it just wasn't feasible to keep building up. In the late 1800s, new technology redefined these limits. Suddenly, it was possible to live and work in colossal towers, hundreds of feet above the ground. Thousands of workers toiled on the pyramids of ancient Egypt, the cathedrals of Europe and countless other towers, while striving to create something awe-inspiring.

3 How were the great pyramids built? How are giant skyscrapers built? Historians think that the ancient Egyptians used ramps to push or pull the stones to the top. But whether they used one ramp straight up each side or they used a ramp parallel to each side is still being debated. Overcoming the force of gravity, wind and getting materials to greater heights are just some of the obstacles in designing and building skyscrapers. These problems are solved using science and technology by developing mechanical systems that make building skyscrapers possible. A Ramp

4 What is a machine? It is a device with moving parts that work together to accomplish a task. The great pyramids and skyscrapers were built using machines and mechanical systems. Ramps Pulley Systems Ramps and Pulleys

5 Wheel and Axle Gears Levers Ramps Block and Tackle Review of Simple Machines

Classify each of these simple machines.

7 Machines… …make our lives easier. Try cutting down a tree without a saw. A complex machine like a chainsaw makes our lives even easier. Try opening a can without a can opener.

8 Input - Output - Is everything you do to make the machine work. You push the pedals. Is the result of your work. You go fast. There are two basic factors to keep in mind when studying mechanical systems:

9 Input, Output, and Resistance Input Output Resistance effort

10 Mechanical Advantage Little effort Big Results

11 FoFo FiFi MA = Output force (N) Input force (N)

12 Input Output Input Output How can you make it easier to lift the rock? Resistance

13 Input Output Which lever would make it easier to lift the rock? Mechanical Advantage Results 1 m 0.5 m 0.5 m / 1 m = 0.5 Distance

14 Input Output Which lever would make it easier to lift the rock? Resistance 0.1 m 1 m Mechanical Advantage 1 m / 0.1 m = 10

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16 Input Output Input Output Which lever is more efficient? Resistance

17 Input Force Output Which lever is more efficient? Efficiency 5 N 10 N / 5 N = 2 10 N

18 Which lever is more efficient? Input Force 10 N 5 N Efficiency 5 N / 10 N = 0.5

19 (RE) DESIGN PROTOTYPE TEST EVALUATE

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22 Work Formula F d W F x d = W Work (joules) Force (newtons) Distance(meters)

23 Calculating Work in Joules 1 meter 50 N1 m = 50 joules 50 N x 1 m = 50 joules 50 N Force (N)Distance (m) = Work (joules) Force (N) x Distance (m) = Work (joules) 50 N 50 newton1 meter How many joules would be needed to lift a 50 newton rock 1 meter?

24 An inclined plane is a slanted surface used to raise a load from a lower level to a higher level. 2 meter The 2 meter ramp reduces the force from 50 N to 25 N. 1 meter 2 meters 25 newtons (effort) 25 N2 m = 50 joules 25 N x 2 m = 50 joules with less  force… 50 Nrock 25 newtons You can reduce the effort force required to lift the 50 N rock by using a 2 meter ramp. Since the distance the rock is moved is doubled, the effort force is reduced by ½ to 25 newtons. Force (N)Distance (m) = Work (joules) Force (N) x Distance (m) = Work (joules)

25 50 N 2 m rock 1 m 25 N. This 2 m ramp enables 50 N rock to be lifted 1 m with a force of 25 N. Which inclined plane would be best to lift a rock 1 meter in height? 1 meter 2 meters 5 meters 10 newtons (effort) 25 newtons (effort) 1 meter 25 N2 m=10 N5 m 25 N x 2 m = 50 joules = 10 N x 5 m 5 m rock 1 m 10 N. This 5 m ramp enables 50 N rock to be lifted 1 m with a force of 10 N. 10 N5 m 10 N x 5 m = 50 joules 25 N2 m = 50 joules 25 N x 2 m = 50 joules Force (N)Distance (m) = Work (joules) Force (N) x Distance (m) = Work (joules) System A System B

26 1 meter  Force  distance  Force X  distance  Force  distance  Force X  distance = F x d = W System A System B The WORK is EQUAL in Both Systems. Machines and mechanical systems DO NOT reduce the amount of work, they just make work easier!