What are the types of force and motion, and how do levers and linkages give mechanical advantage and change motion?
Forces, stresses and motion: tension, compression, bending, torsion and shear, the four types of motion (linear, rotary, reciprocating, oscillating), levers and the three lever classes, mechanical advantage, and linkages that change the direction or type of motion.
A focused answer to Eduqas GCSE Design and Technology (C600) on forces, stresses and motion: tension, compression, bending, torsion and shear, the four types of motion, levers, lever classes and mechanical advantage, and linkages.
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What this dot point is asking
Eduqas C600 expects you to understand forces and stresses, the types of motion, and levers and linkages. You need the five forces (tension, compression, bending, torsion, shear), the four types of motion (linear, rotary, reciprocating, oscillating), the three lever classes and mechanical advantage, and how linkages change motion. In the written exam this is tested by naming forces or motions and by Explain questions on how a lever gives mechanical advantage.
Forces and stresses
A material can be strong against one force and weak against another, so the first step is to identify the force, then choose a material and shape to resist it.
Types of motion
The common confusion is reciprocating versus oscillating: a jigsaw blade reciprocates (straight up and down), while a pendulum oscillates (swings through an arc). Being precise about which a part shows is a frequent exam point.
Levers and mechanical advantage
Levers come in three classes by the order of pivot, load and effort:
- Class 1: pivot in the middle (a seesaw, scissors, a crowbar).
- Class 2: load in the middle (a wheelbarrow, a bottle opener); always gives a mechanical advantage.
- Class 3: effort in the middle (tweezers, a fishing rod, the human forearm); trades force for speed and range.
Linkages connect levers to change the direction of a force or the type of motion (for example a reverse-motion linkage makes an output move opposite to an input).
Try this
Q1. Name the force acting on a screwdriver shaft as you turn a stiff screw. [1 mark]
- Cue. Torsion (a twisting force).
Q2. State which lever class always gives a mechanical advantage. [1 mark]
- Cue. Class 2 (load between the pivot and the effort).
Exam-style practice questions
Practice questions written in the style of WJEC Eduqas exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
Eduqas C600 20183 marksName the four types of motion and give an example of each.Show worked answer →
A 3-mark question covering all four types with examples (full marks need all four correctly matched).
Linear: movement in a straight line, for example a drawer sliding out or a lift moving up.
Rotary: movement in a circle, for example a wheel turning or a drill bit spinning.
Reciprocating: straight-line movement backwards and forwards, for example a sewing-machine needle or a jigsaw blade.
Oscillating: swinging backwards and forwards through an arc, for example a pendulum or a swing.
Markers reward each correctly named type with a matching example. The common confusion is reciprocating (back and forth in a straight line) versus oscillating (swinging through an arc), so be precise about each.
Eduqas C600 20214 marksA wheelbarrow is a class 2 lever. Explain how it gives a mechanical advantage, referring to the pivot, load and effort.Show worked answer →
A 4-mark Explain wants the lever class and the mechanical advantage explained.
In a wheelbarrow the pivot is the wheel at the front, the load (the contents) is in the middle, and the effort (lifting the handles) is at the far end. This is a class 2 lever, with the load between the pivot and the effort.
Because the effort is applied further from the pivot than the load, a small effort over a large distance lifts a large load over a small distance, giving a mechanical advantage: the user lifts a heavy load with less force than its weight.
Markers reward identifying the pivot (wheel), load (middle) and effort (handles), and explaining that the effort acting further from the pivot than the load gives a mechanical advantage. Getting the lever class or the order wrong loses marks.
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Sources & how we know this
- WJEC Eduqas GCSE (9-1) Design and Technology (C600) specification — WJEC Eduqas (2017)