Question

key concept builder
lesson 3
simple machines
key concept how are simple machines and compound machines different?
directions: answer each question on the lines provided.

1. what is a compound machine?
2. how is the efficiency of a compound machine calculated?
3. what happens to the efficiency of the overall machine as more simple machines are added to it?
4. how can gears change the size and direction of a force?
5. explain why a wedge that splits wood is an example of a compound machine.
6. suppose the efficiency of the wedge portion of a wedge that splits wood is 90 percent (or 0.9) and the efficiency of the lever part of it is 80 percent (or 0.8). what is the efficiency of the machine?

Explanation:

Step1: Calculate the efficiency of the compound machine

The efficiency of a compound machine is calculated by multiplying the efficiencies of its component simple machines.
$$\text{Efficiency}=\text{Efficiency of wedge}\times\text{Efficiency of lever}$$

Step2: Substitute the given values

Given that the efficiency of the wedge is \(0.9\) and the efficiency of the lever is \(0.8\).
$$\text{Efficiency}=0.9\times0.8$$

Step3: Perform the multiplication

$$0.9\times0.8 = 0.72$$

Answer:

The efficiency of the machine is \(0.72\) or \(72\%\)