Speed Time Distance Calculations Answer Key Great Intro Classwork ... - Free Printable

You’ve uploaded a worksheet titled “DISTANCE, TIME, SPEED PRACTICE PROBLEMS” with handwritten answers and calculations. The goal is to solve the problems and explain the solution — which you’ve already done! But since you’re asking for an explanation of the solutions, I’ll walk through each problem step-by-step, validate your answers, and explain the reasoning.

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## 📌 Key Formulas Used:

- Speed = Distance ÷ Time → `S = d / t`
- Time = Distance ÷ Speed → `t = d / s`

Units must be consistent (e.g., meters with seconds, kilometers with hours).

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# ✔ Problem 1:
> If a car travels 400m in 20 seconds, how fast is it going?

Your Answer: 20 m/s — ✔️ Correct

Explanation:
```
Speed = Distance / Time
= 400 m / 20 s
= 20 m/s
```
This means the car covers 20 meters every second.

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# ✔ Problem 2:
> If you move 50 meters in 10 seconds, what is your speed?

Your Answer: 5 m/s — ✔️ Correct

Explanation:
```
Speed = 50 m / 10 s = 5 m/s
```
You’re moving at a steady pace of 5 meters per second.

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# ✔ Problem 3:
> You arrive in class 45 seconds after leaving math, which is 90 meters away. How fast did you travel?

Your Answer: 2 m/s — ✔️ Correct

Explanation:
```
Speed = 90 m / 45 s = 2 m/s
```
You walked at 2 meters per second — reasonable walking pace.

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# ✔ Problem 4:
> A plane travels 395,000 meters in 9000 seconds. What was its speed?

Your Answer: 44 m/s (rounded from 43.8) — ✔️ Correct

Explanation:
```
Speed = 395,000 m / 9000 s ≈ 43.888... m/s
Rounded to nearest whole number → 44 m/s
```
Note: 44 m/s is about 158 km/h — a reasonable speed for a small aircraft or takeoff/landing phase.

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# ✔ Problem 5:
> It takes Serina 0.25 hours to drive to school. Her route is 16 km long. What is her average speed?

Your Answer: 65 km/h — ❗ Slight error here!

Wait — let’s recalculate:

```
Speed = Distance / Time
= 16 km / 0.25 h
= 64 km/h
```

✔ Correct answer should be 64 km/h, not 65.

Why?
0.25 hours is 15 minutes.
16 km in 15 minutes → in 60 minutes (1 hour), she’d go 4 × 16 = 64 km.

➡️ Correction: Your answer is slightly off — likely due to rounding or calculation error.
Correct Answer: 64 km/h

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# ✔ Problem 6:
> How much time will it take for a bug to travel 5 meters across the floor if it is traveling at 1 m/s?

Your Answer: 5 s — ✔️ Correct

Explanation:
```
Time = Distance / Speed
= 5 m / 1 m/s = 5 seconds
```
Simple and straightforward.

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# ✔ Problem 7:
> You need to get to class, 200 meters away, and you can only walk in the hallways at about 1.5 m/s. How much time will it take?

Your Answer: 133 s (rounded from 133.3) — ✔️ Correct

Explanation:
```
Time = 200 m / 1.5 m/s ≈ 133.333... s
Rounded to nearest whole number → 133 s
```
That’s about 2 minutes and 13 seconds — realistic for walking.

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# ✔ Problem 8:
> In a competition, an athlete threw a flying disk 139 meters through the air. While in flight, the disk traveled at an average speed of 13.0 m/s. How long did the disk remain in the air?

Your Answer: 13 s — ✔️ Correct

Explanation:
```
Time = 139 m / 13.0 m/s ≈ 10.692... s
Wait — this doesn’t equal 13 s!
```

⚠️ Error Detected!

Let’s recalculate:
```
Time = Distance / Speed
= 139 m / 13.0 m/s
≈ 10.692 seconds
```

Rounded to nearest whole number → 11 seconds, not 13.

➡️ Correction: Your answer of “13 s” is incorrect. The correct answer is approximately 10.7 s, or 11 s when rounded.

Possible cause of error: Maybe you divided 139 by 10.7 instead of 13? Or misread the numbers?

✔ Correct Answer: ~10.7 seconds (or 11 s rounded)

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# 📝 Summary of Corrections:

| Problem | Your Answer | Correct Answer | Notes |
|---------|-------------|----------------|-------|
| 5 | 65 km/h | 64 km/h | Calculation error |
| 8 | 13 s | ~10.7 s | Major error — recheck division |

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# 🧠 Final Tips:

- Always double-check your arithmetic, especially with decimals.
- Keep units consistent — don’t mix km with meters or hours with seconds unless you convert.
- Rounding should be done *after* calculation, not during.
- Show all steps clearly — you did great with that!

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✔ Overall, you did very well! Most of your work is accurate and shows clear understanding of the formulas. Just watch out for small calculation slips — they happen to everyone!

Let me know if you’d like to redo Problems 5 and 8 with corrected steps! 😊