(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

An athlete executing a long jump leaves the ground at a 20° angle and travels 7.80 m.

(a) What was the takeoff speed?

2. Relevant equations

Trigonometry- 3.6tan(20)=1.42 which is the max height

Vy² = Vyo² + 2a(y-yo) to find initial velocity

Vy = Vyo + at to find time

x = xo + Vxot + 1/2at² to find velocity initial

3. The attempt at a solution

3.6tan(20)=1.4194839136381892092690867428297m is the meters for max height.

Vy² = Vyo² + 2(-9.8m/s²)(1.4194839136381892092690867428297)

Vyo² = 27.821884707308508501674100159461m/s

Vyo = 5.2746454579723657955166904897785m/s

Vy = 5.2746454579723657955166904897785m/s + (-9.8m/s)t

t = 0.53822912836452712199149902956923s

0.53822912836452712199149902956923s x 2 = 1.0764582567290542439829980591385s for total hang time

7.8m = 0m + Vxo1.0764582567290542439829980591385s + 1/2(0m/s²)(1.07646)²

Vxo = 7.2459846457039799434766682275793

This is not the correct answer, or so I'm told. I also tried twice the velocity for 14.491969291407959886953336455159 but it is still incorrect.

I know it is something similar to this because there is another part, "(b) If this speed were increased by just 6.0 percent, how much longer would the jump be? "

For this the answer resulted to be 0.96407999999999999999999999998m, which is correct. I think this means that I am on the right track, but need to put the correct number choice. Any inputs on possible numbers would be appreciated.

edit:I was told of another number that could be possible, 10.9, but I don't know how this number was reached, or if it is correct. Just thought I'd put it out

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# Homework Help: Projectile Motion long jumper Problems

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