Unit 2, Chapter 4

Integrated Science

Unit Two: Work and Energy

4.1 Force and Machines

4.2 The Lever

4.3 Gears and Design

Chapter 4 Machines and Mechanical Systems

Chapter 4 Learning Goals Describe and explain a simple machine. Apply the concepts of input force and output force to any machine. Determine the mechanical advantage of a machine. Construct and analyze a block and tackle machine. Describe the difference between science and engineering. Understand and apply the engineering cycle to the development of an

invention or product. Describe the purpose and construction of a prototype. Design and analyze a lever. Calculate the mechanical advantage of a lever. Recognize the three classes of levers. Build machines with gears and deduce the rule for how pairs of gears

turn. Design and build a gear machine that solves a specific problem.

Chapter 4 Vocabulary Terms engineering gear

engineering cycle

engineers

force

fulcrum

gear

input

input arm

input force

input gear

lever machine mechanical advantage mechanical systems output output arm output force output gear prototype simple machine

4.1 Forces in Machines

Key Question:

How do simple machines work?

*Read text section 4.1

AFTER Investigation 4.1

4.1 Mechanical Advantage

MA = Fo

Fi

Output force (N)

Input force (N)

mechanicaladvantage

4.2 The Lever

Key Question:

How does a lever work?

*Read text section 4.2

AFTER Investigation 4.2

4.3 Gears and DesignKey Question:

How do gears work?

*Read text section 4.3

AFTER Investigation 4.3

4.3 Gear Ratios

To = Ni

Ti No

Number of teethon input gearTurns of output gear

Turns of input gearNumber of teeth

on input gear

Machines