Work, Power, and Simple Machines Presentation (MFE 4:1 & 4:3)

Formal Definition: Work is occurs when an applied force makes an object move in the same direction as the applied force.
Formula for Work: $work = force \times distance$ or $w = f \times d$ .
Units of Measurement: - Work: Joules ( $J$ ). - Force: Newtons ( $N$ ). - Distance: Meters ( $m$ ).

In order for work to happen, two specific conditions must be met:

A force has to be applied to an object.
The object has to move a distance in the same direction as the force being applied.

Work Example (Car): The force (pull) is exerted to the right, and the car moves to the right.
Work Example (Lifting): The force (lift) is upward, and the weight moves upward.
Not Work Example (Carrying): The force (lift) is upward, but the box is moving forward (horizontally). Because the motion and force are not in the same direction, work is not being done on the box in the direction of travel.

Carrying Down a Hallway: If you are carrying a basket of laundry while walking down a hall, you are not doing work. The force applied to the laundry basket to overcome gravity and pick it up is vertical, while the motion of the basket is horizontal. Since these directions do not match, work is not occurring.
Walking Up Stairs: As soon as you walk up the stairs, you are doing work. In this case, the force is vertical (required to overcome gravity) and the motion is also vertical.

Sometimes the force is only partially in the direction of motion, such as when dragging a heavy bag.
When dragging a bag, you lift up slightly as you drag, applying force in two directions: vertical and horizontal.
Because the bag is only moving across the floor (horizontally), only the portion of the force applied in the horizontal direction is considered "work."

Definition: Power is the amount of work done on an object in a unit of time.
Characteristics of Power: A more powerful object can perform more work in the same amount of time, or perform the same amount of work in less time.
Formulas for Power: - $Power = \frac{work}{time}$ - $Power = \frac{force \times distance}{time}$
Units of Measurement: - Joules per second ( $J/s$ ). - Watts ( $W$ ).

Definition: A simple machine is a device that makes work easier by changing the amount of force needed, the direction of the force, or both, in order to move an object.
The Six Simple Machines: 1. Inclined Plane 2. Lever 3. Pulley 4. Screw 5. Wedge 6. Wheel and Axle

Definition: A simple machine consisting of a sloping surface that connects a lower elevation to a higher elevation.
Mechanism: It decreases the amount of FORCE needed to do work but increases the DISTANCE over which that force must be applied.
Examples: - Wheelchair ramp. - Boat ramp (referenced with labels $FX4$ and $FL8627NL$ ). - Slide.

Definition: A simple machine consisting of a bar that rotates around a fixed point known as a fulcrum.
Mechanism: It changes the amount and/or the direction of the FORCE to something more "convenient."
Examples: - Seesaw (teeter-totter). - Wheelbarrow. - Tweezers.
The Three Classes of Levers: - 1st Class: The fulcrum is located between the force and the load (Example: seesaw). - 2nd Class: The load is located between the force and the fulcrum (Example: wheelbarrow). - 3rd Class: The force is located between the load and the fulcrum (Example: baseball bat).

Definition: A simple machine that consists of a rope and a grooved wheel.
Mechanism: It changes the amount and/or direction of the FORCE needed to do work but increases the DISTANCE.
Examples: - Pulleys at the top of flagpoles. - Pulleys at the top of sailboat masts. - Elevators.
Data Point: A pulley system is shown lifting a mass of $7000\,kg$ .

Definition: A simple machine that consists of an inclined plane wrapped around a central cylinder.
Mechanism: It decreases the amount of FORCE needed to do work but increases the DISTANCE.
Examples: - Jar and bottle lids (referenced with "CRUSH Orange 1.25"). - Lightbulb bases. - Screws.

Definition: A simple machine consisting of two inclined planes, resulting in a thin end and a thick end.
Mechanism: It increases the amount of the FORCE needed to do work but decreases the DISTANCE.
Examples: - Axe. - Scissors. - Knife.

Definition: A simple machine consisting of two connected rings or cylinders, where one is positioned inside the other.
Mechanism: It decreases the amount of FORCE needed to do work but increases the DISTANCE.
Examples: - Wheels. - Gears. - Tires.

Definition: A compound machine is a machine that combines two or more simple machines into one system.