Year 7 Science · Unit 3 · Lesson 17
Apply Worksheet
Learning Goals
Order the steps
Number the steps from 1 to 7 to show the correct sequence for setting up and using a movable pulley to lift a 200 kg engine block in an Australian auto mechanic workshop. Step 1 = what happens first.
| Order | Step |
|---|---|
| Pull the free end of the rope downward — the engine block begins to rise slowly. | |
| Thread one end of the rope through the fixed pulley attached to the overhead beam. | |
| Attach the movable pulley to the lifting hook on the engine block. | |
| Anchor the fixed pulley securely to a load-bearing beam above the engine bay. | |
| Thread the rope down and through the movable pulley attached to the engine block. | |
| Check that the engine block is fully clear of the car before swinging it to the side. | |
| Secure the rope end to a fixed anchor point on the beam to lock the load in place. |
Compare the three classes of lever
Complete the table to compare Class 1, Class 2, and Class 3 levers. Use the lesson to fill in all cells.
| Feature | Class 1 lever | Class 2 lever | Class 3 lever |
|---|---|---|---|
| Which part is in the middle? | |||
| Order of F / E / L along the lever | |||
| Mechanical advantage (MA) | |||
| Do you use less or more force than the load? | |||
| Everyday Australian example |
1. A student says "if I use a longer crowbar to pry up a rock, I'm creating more energy to lift it." Identify the mistake in this reasoning and correct it using the idea of mechanical advantage and trade-offs.
2. Tower cranes in the Sydney CBD use block-and-tackle pulley systems with many rope segments. Explain what happens to the effort force required as more rope segments are added, and what the trade-off is.
Wrap Up
In one sentence, what was the main idea of this lesson?