Machines Learning - Physics

Screw: If the mechanical advantage of a screw is 1.2, and its diameter is 2 cm, what is its pitch in meters?

0.053 m [(3.14 * 0.02 m)/1.2]

Wedge: If the mechanical advantage of a wedge is 5, and its thickness is 0.2 m, what is its length?

1 m (= 5*0.2)

I apply a 6 N force on a box to push it a distance of 4 m. What is the work done?

24 Joules (6 N * 4 m)

How machines make work easier?

A machine cannot do work. A machine does not enable you to do less work; rather it enables you to use less force.

complex machine

A machine that operates by combining two or more of the six simple machines.

Pulley M.A.

Numbers of ropes/cables supporting load.

quantitative

Relating to a number or quantity.

Newton

SI unit for force.

meter

SI unit for length.

Wheel & axle M.A.

wheel radius/axle radius

mechanical advantage

a mathematical expression for how much easier the machine makes work.

Example of pulley

crane, elevator, flagpole, etc.

Lever M.A.

effort arm/load arm

Drill

screw

Example of lever

seesaw, balance scales, crowbar, wheelbarrow, nutcracker, bottle opener, tweezers, fishing rod, hammer, boat oar, rake, etc.

F, L, E - 1, 2, 3

A rhyme to remember the classes of levers: fulcrum in class 1, load in class 2, effort in class 3 - in the center of the lever

Pulley

A simple machine consisting of a grooved circular wheel which guides a rope, cable or chain. This machine is primarily used to lift heavy loads along a direct vertical path.

wedge

A simple machine consisting of a piece of wood or metal that is thicker at one end than the other. This machine transfers a downward force into an outward force.

inclined plane

A simple machine consisting of a ramp or other angled surface allowing people to lift objects using less force.

lever

A simple machine consisting of a rigid beam or bar which pivots about a fixed point to move heavy loads with less effort.

screw

A simple machine consisting of a spiral ridge wrapped around a rod or cylinder, working like an inclined plane. This machine converts a rotational force into a longitudinal force.

wheel & axle

A simple machine consisting two circular or cylindrical objects which are fastened together and rotate about a common axis. Primarily used to magnify a torque supplied by the user.

force

Any push or pull.

Rube Goldberg

Cartoonist and engineer who poked fun at overly complicated machines; a machine that operates in a complicated way in which the procedure could have been much simpler.

Ideal mechanical advantage

The advantage a machine provides under ideal circumstances or without the presence of friction.

Pencil sharpener

The blade that cuts and sharpens the pencil is a wedge. A screw holds the pieces together. The piece you spin is a wheel and axle.

structural engineering

The branch of civil engineering that is responsible for the design of structures.

work

The energy spent moving an object over a distance using force (W = Fd).

simple machine

The fundamental parts of any machine. Simple machines can exist on their own and are also sometimes hidden in the mechanical devices around you; a device which performs work by increasing or changing the direction of force, making work easier for people to do.

Manual can opener

The handle you rotate is a wheel and axle. The two long arms that clamp make a lever. The circular wheel that cuts the metal lid is a sharp wedge.

logic

The interrelationship between elements of a whole.

M.A. = 1

The machine does nothing and work is the same.

M.A. < 1

The machine magnifies the input distance (work is harder but much faster).

M.A. > 1

The machine magnifies the input force (work is easier but slower).

Screw M.A.

dπ/pitch (height of screw thread)

Wedge M.A.

length/thickness

Bicycle, wheelbarrow, scissors

lever, wheel and axel

Example of wheel & axle

screwdriver, steering wheel, bicycle gears, doorknob, etc.

If each simple machine had a mechanical advantage of 2, what is the mechanical advantage of the compound machine (consists of 6 simple machines)?

12 (It has 6 simple machines, each with a mechanical advantage of 2, so the total mechanical advantage is 12.)

A construction worker uses a board and log as a lever to lift a heavy rock. They apply a force of 20 N without the use of the lever, however with the lever, they apply a force of 10 N. What is the mechanical advantage?

2 (20 N / 10 N)

Inclined Plane: If the slope length of an inclined plane is 9 m, and the height is 3.5 m, what is its mechanical advantage?

2.57 (= 9/3.5)

Wheelbarrow

A 2nd class lever combined with a wheel and axle to make it roll.

Average

A mathematical calculation used to predict or understand a phenomenon.

model

A pattern of something to be made.

Constraint

A restriction or limitation.

Compound machine

Consists of two or more simple machines and allows for work to be done easier.

Work is defined as the product of force and distance. Which one of these things, force or distance, makes work fast or slow?

Distance. (If a machine can reduce the distance required to do work, it is generally faster to carryout the work, even though it is harder to do.)

From the previous scenario, who did the work easier?

Emma (used a force of only 50 lbs. while engineer Ed used a force of 200 lbs.)

Who does more work: engineer Ed lifts a 200 lb. weight up to a height of 2 ft. and engineer Emma lifts a 50 lb. weight to a height of 8 ft.?

Equal (W = Fd)

T/F: The inclined plane has more mechanical advantage than both the wedge and screw.

False (While every simple machine provides mechanical advantage, each machine does not have a specific mechanical advantage associated with it. An engineer has the option to design an inclined plane with a mechanical advantage of either 2 or 200. Remember, an engineer may complete the same amount of work in many different ways, although some ways are easier than others.)

True or False: The lever has four different components.

False. (The lever has three main components; the fulcrum, effort and load. These components can be arranged in three different ways and so the lever has three different classifications.)

True or False: The lever is a better simple machine than either the pulley or wheel and axle.

False. (While the lever may be a better choice for engineers in a specific design, one machine is not superior to another. Every simple machine has its own unique advantages which can be used for different engineering applications.)

Work is defined as the product of force and distance. Which one of these things, force or distance, makes work harder to do?

Force. (If a machine can reduce the force required to do work, it is generally easier to apply it over a longer distance.)

The difference between ideal mechanical advantage and actual mechanical advantage.

Only ideal mechanical advantage can be determined in advance. Ideal mechanical advantage is the advantage a machine provides under ideal circumstances or without the presence of friction. The actual mechanical advantage is determined after the input and output forces are measured and accounts for the unfavorable effect of friction in a machine. Since friction is a force which opposes motion, the actual mechanical advantage of a machine is always less than its ideal mechanical advantage: IMA ≥ AMA.

Inclined plane M.A.

Slope length (distance)/ height

load

The object being moved by the lever.

torque

The result of applying a linear force at the outside of a circular frame to create a turning tendency.

Corkscrew

The rotating handle at the top is a wheel and axle. The spiral metal piece that secures the cork is a screw. The sharp tip on the bottom of the spiral piece is a wedge to dig into the cork before turning. The two side arms that are pushed down are levers.

T/F: The wedge and screw can be thought of as slight variations of the inclined plane.

True (The wedge is composed of two inclined planes set back to back and the screw is composed of wrapping an incline around a cylinder.)

metric units

Units of measurement as defined under the International System of Units (SI).