Question #b43b8

2 Answers
Sep 29, 2015

I found 28m/s directed downwards.(but check my maths)

Explanation:

When the object comes back (passing through the releasing point again) it'll have a velocity of 13.3m/s but directed downwards (neglecting anty air resistance)!
So we have:

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Sep 29, 2015

v = -"27.5 m/s"

Explanation:

So, you know that an object is being thrown straight upwards from an unknown height h above the ground with an initial velocity of "13.3 m/s".

At meximum height, the velocity of the object will be equal to zero, which means that you can say

underbrace(v_"top"^2)_(color(blue)(=0)) = v_0^2 - 2 * g * h_1

The distance the object travels before reaching maximum height will thus be

h_1 = v_0^2/(2 * g) = (13.3^2 "m"^2color(red)(cancel(color(black)(2))) color(red)(cancel(color(black)("s"^(-2)))))/(2 * 9.8color(red)(cancel(color(black)("m"))) color(red)(cancel(color(black)("s"^(-2))))) = "9.03 m"

Now, you know that you must determine the object's velocity when it is located "29.6 m" below the point of its release.

This is equivalent to saying that you must find its velocity after the fell for a total of

"9.03 m" + "29.6 m" = "38.63 m"

So, if the object is free falling for a distance of "38.63 m", then you can say that

v_"x"^2 = underbrace(v_"top"^2)_(color(blue)(=0)) + 2 * g * "38.63 m"

The velocity of the object will thus be

v_"x" = sqrt( (2 * 38.63"m" * 9.8"ms"^(-2))) = "27.5 m/s"

If we take the upwards direction to be the positive direction, then the velocity of the object will be

v_"x" = color(green)(-"27.5 m/s")