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The Six Simple Machines Assignment

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Jielex Songcuan

on 11 March 2013

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Transcript of The Six Simple Machines Assignment

Levers: Pulleys: Wheel and Axle: Inclined Plane: Screws: The Six Simple Machines
Levers change the amount of force/effort you must apply in order to move an object. They make work easier because they help the user lift heavy loads, move things at a greater distance or move it to a specific spot (precision) and provide speed. This all depends on what class the lever is. There are three classes; 1st class, 2nd class and 3rd class. The location of the fulcrum, effort, and load can all determine what class the lever is. The fulcrum is the point of rotation or the fixed point and it supports the lever. The effort force is the force you put on the lever to make it move. It is used to describe the force applied to any machine in order to create action. Lastly, the load, also known as resistance, is what you’re trying to lift. First Class Levers: Class 1 levers always have the fulcrum in the middle. They change the direction of force because when you push down, the load goes up. Class 1 levers also for power (they make it easier to lift heavy loads). They also are used for precision. Where the fulcrum is located will determine whether the load will go at a longer distance or if you want it at shorter distance. When the fulcrum is closer to the load arm, it will decrease the amount of force you need to exert and when you apply the force, it’ll go at a longer distance. When the fulcrum is closer to the effort arm, it increases the force you need to apply but it makes it easier to be more precise about where you want to move the load. Examples include: scissor and seesaws. Mechanical Advantage or MA refers to how much machines make work easier by multiplying the effort you put into it. Second Class Levers: Class 2 levers always have the load in the middle. They are used for power, which means they provide aid to the user to lift heavy loads. An example is a wheelbarrow. Wheelbarrows have the effort force on the end and it’s when the user is pushing on it. The load is in the middle, which is what’s inside the wheelbarrow. The fulcrum is the wheel on the other end. Third Class Levers: Class 3 levers always have the effort force in the middle. It is used for speed. An example is a hockey stick. At the end of the stick is the fulcrum because it always stays in place in the player’s hands. The middle is the effort because the force is being applied their so that the hockey stick moves. At the end is the load because it’s where you’re hitting the puck which provides it speed. The wheel and axle involves two turning objects attached at their centres. It doesn’t necessarily have to be round but one must make the other turn. They make work easier because they reduce friction which makes it easier to move an object. The force is applied to the wheel or axle in order for rotation to happen. When the force is applied to the wheel and it moves the axle, the mechanical advantage is making it easier for force. When the force is applied to the axle and it moves the wheel, the mechanical advantage is usually for speed. A door knob is an example for when the wheel is turned to make the axle move. You’re turning the knob, which in this case is the wheel, so that it can turn the axle. It depends on how much force you apply to the wheel so you can get the door to open. It made work easier because if you don’t have a door knob on a door it would be harder to open the door. This is an example when the axle is turned; the wheel is then turned in result. You apply the force on the pedal which turns the axle. Then, when the axle is turned, the wheel is also turned. The bicycle is another example and they make work easier because it’s easier to transport yourself to another place using a bicycle rather than walking. Pulleys make work easier because they distribute the work so it’s easier to lift the load. This simple machine consists of a grooved wheel with a wire, rope, cable, etc. running along the groove. A fixed pulley is a type of pulley where the pulley is attached to something that is in a fixed position. This pulley is used to change the direction of the force. For example, when the effort force is pulling down the load goes up. This is what happens on a flag pole. When you pull down on the rope, it lifts up the flag. An inclined plane is a ramp or slope. It makes work easier because it reduces the force you need to use to lift something. The picture shows you a person pushing a wardrobe into a truck using a ramp. A ramp is an example of an inclined plane. It makes work easier because without the ramp, they would have to lift the wardrobe up which would be really hard because it’s heavy. When the person uses the ramp they just have to push so they don’t use a lot of force. A screw is a wedge wrapped around a cylinder to turn to move up and down. Screws make work easier because they’re easier to get in things, such as wood. Let’s compare nails and screws. Nails are sharp and straight but it takes a really long time and a lot of force to get into wood. You have to bang it into the wood with a hammer so many times. Screws on the other hand, they have a wedge that’s wrapped around them and when you twist it into the wood, you’re not applying as much for. If we also compare their qualities, screws have a higher quality because the wedge that’s wrapped around will make it so that it will take a longer time for the screw to come off because you’ll have to untwist it. For nails, you can just pull it out with a hammer and it all of a sudden comes out. Archimedes Screw Wedges: A wedge is an object that has at least one slanting side with a sharp edge. Wedges cut materials apart. They make work easier by making it easier to cut things into parts. For example, if you use your hand to cut a piece of wood, it would be hard because your hand doesn’t have a sharp edge. If you use an axe, it’ll be easier because the sharp edge will cut it in half. Short wedges may do the job faster but it takes more force than a long edge with a narrow angle. Some examples include knives and chisels. Mechanical Advantages: Levers: Wheel and Axle: Pulleys: Inclined Plane: Screw: Mechanical Advantage or MA refers to how much machines make work easier by multiplying the effort you put into it. MA = Length of Effort Arm

Length of Load Arm
Example:
-Effort arm is 15 cm long and the load arm is 5 cm long.
-15÷5=3
- So the MA would be 3.



MA= Diameter of Wheel
Diameter of Axle
Example:
-The diameter of the wheel was 18 cm and the diameter of the axle was 6.
-18÷6=2.
- So the MA would be 2.
MA= Total # of Strands that Support a Load.

So in a fixed pulley the mechanical advantage is on because there is only one “lifting rope”. MA= Length of Plane
Height of Plane
Example:
Let’s take the picture of the person pushing the wardrobe using a ramp. If the length of the plane was 6 metres and the height of the plane was 3 the MA would be 2. 6÷3=2 MA= Circumference
Pitch Wedges: MA = Length of Wedge

Width of Load Arm Example:
- Axe was 40 cm long and 5 cm wide.
- 40÷5=8.
- So the MA would be 8.
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