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A Level Mechanics

Variable Acceleration

Learn variable acceleration as part of model motion, forces, moments, friction, projectiles and variable acceleration.

Key idea

Draw a model first, define the direction of motion, then choose the equation that matches the known quantities.

What you will learn

Use variable acceleration meaning confidently.
Use variable acceleration representations confidently.
Use variable acceleration methods confidently.
Use variable acceleration applications confidently.

Success checklist

āœ“I can explain what variable acceleration means.
āœ“I can choose a suitable method without being told.
āœ“I can show clear working and check my answer.

Worked example

A particle starts from rest and accelerates at 2 š‘š/š‘ Ā² for 5 s. Find š‘£.

Model method

Step 1

Use š‘£ = š‘¢ + š‘Žš‘”.

Step 2

Here š‘¢ = 0, š‘Ž = 2 and š‘” = 5.

Step 3

š‘£ = 0 + 2 Ɨ 5 = 10.

Answer

10 š‘š/š‘ 

Quick practice

Question 1

Find F when š‘š = 4 kg and š‘Ž = 3 š‘š/š‘ Ā².

Question 2

Find the moment of a 10 N force acting 0.4 m from a pivot.

Question 3

State the initial vertical velocity for a horizontal projectile.

Related resources

These are linked to the wider Mechanics topic for now.

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