A ball's mass is 1.50 kilograms, and it leaves the racket with a horizontal speed of, say, 90 mph. Find the average force on the tennis ball as it is served.

Question

mhchen · Answer

I'm assuming you the 'horizontal speed' is only the x-component of the actual force right'?

girlstudy · Answer

I guess?

mhchen · Answer

Okay, cause we're going to factor in gravity. Hold on give me a sec. to thikn about it.

mhchen · Answer

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Okay so this is what I'm thinking of. And we have to convert 90miles per hour into m/s

mhchen · Answer

1,609m in a mile, so 144,810 meters / hour.
3600 seconds in an hour so 40.225 m/s

So Fracket = 40.225m/s * 1.5kg = 60.3375N

mhchen · Answer

Then we use pythagorean theorem to do $$\sqrt{60.3375^2+15^2}$$ and that should be it based on my guesses/calculations.

girlstudy · Answer

Why do we use pythagorean theorem?

girlstudy · Answer

How did you get 15N in the beggining? where did the 10m/s come from? @mhchen

girlstudy · Answer

@mathmale

mhchen · Answer

Um...
Force of gravity = mass(kg) * 10m/s^2 (accerlation of gravity)

mhchen · Answer

The vector components of then x and y directions make part of a right-triangle.

blazeryder · Answer

isn't gravity 9.81 m/s^2?  I guess if you wanted to you could round up to 10, but a Physics teacher might not like that.....

irishboy123 · Answer

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@mhchen ?!?!