CalcElf › Thrown up at 50 m/s: height and total time
Thrown up at 50 m/s: height and total time
A ball is thrown straight up at 50 m/s (g = 10). Find the maximum height and the total time until it returns to the thrower's hand.
Answer
Maximum height 125 m, total time 10 s
Step-by-step
- h = v₀²/(2g) = 50²/(2×10) = 125The upward leg ends at speed 0, and v₀² = 2gh gives the maximum height
- t = 2v₀/g = 2×50/10 = 10Rising and falling take equal times, so the total is 2 times the rise time
Why it works
The ball slows at g on the way up, so the height comes from v₀² = 2gh; the upward and downward halves are mirror images, so the total time is twice the rise time.
Common mistakes
- Reporting only the rise time and forgetting the fall.
- Dividing the height by g instead of using v₀² = 2gh.
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