Aprojectile is launched at an angle of 30° and lands 20 s later at the same height as it was launched. (a) what is the initial speed of the projectile? (b) what is the maximum altitude? (c) what is the range?

a) ft/s

b) ft where  represents the height as the projectile was launched.

c) ft

Explanation:

First, recognize the values that are given in the problem:

a) With those three use this formula:

to find the initial velocity .

b) In order to find the maximum altitude, the time is needed to apply the formula. The maximum altitude is when the velocity in the y-axis is equal to zero, so use the formula for the velocity in the y-axis is to find the time, the formula is:

With s use this formula for the altitude:

Finally, the range is the maximum displacement in the x-axis, the formula of the  displacement is:

And the maximum occurs whens

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f=ma newton

f=100x2.5=250n