1. Get out last night’s Homework assignment
Unit 3: Engineering Design
Get out last night’s Homework assignment
A rope is used to pull a metal box 15 m across the floor in 34 seconds. The rope is held at an angle of 45o with the floor and a force of 628 N is used. How much work does the force on the rope do? How much power is consumed? How efficiently is the force being applied to move the metal box?

2. Unit 3: Engineering Design
Topics Covered
Force, Energy, Work, Power, and Efficiency
Topics in Mechanical Engineering
Topics in Electrical Engineering
Engineering Design Process
Teams and Projects
PROJECT: Mechanically Controlled Electromagnetic Crane

3. Simple Machines Machines: Simple Machines:
Devices that use energy to transmit power, force, or motion
Input and Output
Simple Machines:
Devices that transform the direction or magnitude of a force without consuming additional energy
6 simple machines:
Lever: Lever, Wheel and Axle, Pulley
Inclined Plane: Inclined Plane, Wedge, Screw
Much of the information in this lesson, and the way in which it is portrayed, comes from David Macaulay’s The New Way Things Work and the Technology textbook by A. Thomas Wright.
Images: Technology

4. LEVERS Components: Principle of the Lever: F x dF = L x dL 3rd Class
Bar/rod
Fulcrum/pivot
Applied Force
Load
Principle of the Lever:
Static Equilibrium Demonstration
SF = 0 – Sum of Forces equals 0
SM = 0 – Sum of Moments equals 0
F x dF = L x dL
3rd Class
2nd Class
Much of the information in this lesson, and the way in which it is portrayed, comes from David Macaulay’s The New Way Things Work and the Technology textbook by A. Thomas Wright.

5. LEVERS
Much of the information in this lesson, and the way in which it is portrayed, comes from David Macaulay’s The New Way Things Work and the Technology textbook by A. Thomas Wright.

6. INCLINED PLANE Inclined Plane Wedge Screw
Slanted surface used to raise an object
Wedge
Double-sided inclined plane
Used to split, separate, grip
Wood chisel, firewood axe, doorstop
Screw
Inclined plane wound around a central shaft
Identified by diameter and threads per inch
Much of the information in this lesson, and the way in which it is portrayed, comes from David Macaulay’s The New Way Things Work and the Technology textbook by A. Thomas Wright.

7. What’s the point???
Much of the information in this lesson, and the way in which it is portrayed, comes from David Macaulay’s The New Way Things Work and the Technology textbook by A. Thomas Wright.

8. Mechanical Advantage W = F x d Which path takes less work?
Climbing the steep, short cliff face or
Walking the longer, less steep path
It will always take a certain amount of work to lift an object a specific height.
The energy required to perform a task will not change.
We can alter how we do the work or apply the energy.
Much of the information in this lesson, and the way in which it is portrayed, comes from David Macaulay’s The New Way Things Work and the Technology textbook by A. Thomas Wright.

9. Mechanical Advantage MA
Force Multiplier: the number of times a mechanical device multiplies the applied force.
Distance Multiplier: “ the distance the applied force travels.
Let F = 5kg, L = 100kg, and dF = 100cm. What is dL?
Is this a force multiplier or a distance multiplier?
How many times is the applied force multiplied?
Equation:
MA = L / F
MA = dF / dL
Much of the information in this lesson, and the way in which it is portrayed, comes from David Macaulay’s The New Way Things Work and the Technology textbook by A. Thomas Wright.
Image:

10. WHEEL and AXLE 1st, 2nd, 3rd Class Lever
Much of the information in this lesson, and the way in which it is portrayed, comes from David Macaulay’s The New Way Things Work and the Technology textbook by A. Thomas Wright.

11. WHEEL and AXLE 1st, 2nd, 3rd Class Lever
Much of the information in this lesson, and the way in which it is portrayed, comes from David Macaulay’s The New Way Things Work and the Technology textbook by A. Thomas Wright.
Image:

12. Mechanical Advantage
Much of the information in this lesson, and the way in which it is portrayed, comes from David Macaulay’s The New Way Things Work and the Technology textbook by A. Thomas Wright.
Image:

13. Homework
Use dimensional reasoning (and the power-law expression) to determine expressions for the terms on the left side of the equations:
W = f(F, d)
P = f(F, d, t)
F = f(m, a)
Eff = f(output, input)
Complete front side of worksheet by Wednesday’s class
Much of the information in this lesson, and the way in which it is portrayed, comes from David Macaulay’s The New Way Things Work and the Technology textbook by A. Thomas Wright.

14. QUIZ – 1 Problem, 6 parts Show ALL problem solving steps
How much work is required to lift a 100-kg box to a height of 1m?
Now what is the gravitational potential energy of the load?
If the load is dropped from that height, how fast is it travelling when it hits the ground?
If a system with a mechanical advantage of 4 is used to lift the load that distance, what is the required applied force?
How far must that applied force travel in order to move the load the distance of 5m?
If the applied force is in the direction of the displacement, what is the efficiency of the system?
Much of the information in this lesson, and the way in which it is portrayed, comes from David Macaulay’s The New Way Things Work and the Technology textbook by A. Thomas Wright.