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+--- Thread: Acceleration — How Speed Really Changes Over Time (/showthread.php?tid=410)
Acceleration — How Speed Really Changes Over Time - Leejohnston - 01-08-2026
## Acceleration — How Speed Really Changes Over Time
### 1. The Equation
Acceleration = Change in velocity ÷ Time
Often written as:
a = Δv ÷ t
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### 2. What Each Symbol Means
- a = acceleration
- Δv = change in velocity
- t = time
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### 3. What the Equation Is Telling Us
Acceleration measures **how quickly speed or direction changes**.
You can accelerate by:
- speeding up
- slowing down
- changing direction
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### 4. Where It Comes From (Intuition)
Acceleration describes how motion evolves.
A constant speed means **zero acceleration**, even if the object is moving fast.
---
### 5. Worked Example
If a car:
- increases speed from 0 to 20 m/s
- in 5 seconds
Acceleration = 20 ÷ 5
= **4 m/s²**
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### 6. Real-World Applications
- Car safety and braking
- Roller coasters
- Space launches
- Sports performance
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### 7. Common Mistakes
- Confusing speed with acceleration
- Forgetting direction matters
- Assuming acceleration always means speeding up
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### Try It Yourself
What acceleration do you feel when:
- a car brakes suddenly?
- an elevator starts moving?