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AVprozaik [17]
3 years ago
7

A train travels 79 kilometers in 2 hours, and then 77 kilometers in 3 hours. What is its average speed?

Physics
1 answer:
koban [17]3 years ago
4 0
Average speed=total distance traveled/time. Total distance=the sum of the two short distances=79*2+77*3=389 km. Total time used to travel is 2+3=5 hr. Average speed is 389/5=77.8 km/hr.
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Both of these forces however are equal and opposite and therefore, there is zero net force on the box. That's why it remains at rest, holding on Newton's third law.

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g A ball thrown straight up into the air is found to be moving at 7.94 m/s after falling 2.72 m below its release point. Find th
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and

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The ball is falling with a velocity of 7.94 m/s when it's 2.72 m below the release point, which at time <em>t </em>such that

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Solve for <em>t</em> in the second equation:

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Substitute this into the first equation and solve for <em>v</em>₀ :

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2 (-2.72 m) (9.80 m/s²) = 2<em>v</em>₀² + (15.9 m/s) <em>v</em>₀ - (<em>v</em>₀² + (15.9 m/s) <em>v</em>₀ + 63.0 m²/s²)

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<em>v</em>₀² = 9.73 m²/s²

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