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

A soccer ball is kicked at 38.0° with respect to the horizontal and travels 64.0m before striking the ground.

a) what is its initial velocity?

b) how long was it in the air?

2. Relevant equations

d_{v}=1/2*at^{2}

d_{h}=V_{h}*Δt

Kinetic equation d=V_{i}*t+ 1/2*at^{2}

d_{h}=-V^{2}*sin2θ /g

sinθ=opp/hyp

cosθ=adj/hyp

Δt=-2Vsinθ / g

3. The attempt at a solution

a) d_{h}=cos(38)*64m= 50.4m

d_{v}=sin(38)*64m=39.4m

Find t=√(39.4m/(0.5*9.8))=7.96s

plug this value into the d=V_{i}*t+ 1/2*at^{2}equation and solve for V_{i}if d=64m

V_{i}=3.14m/s

b) V=d_{h}/Δt= 50.4m/7.96s=6.33m/s

Then solve for Δt=-2Vsinθ / g= 0.80s

I would like for someone to just double check my answers and that I used the appropriate equations and that the number of significant figures are being respected! Thanks so much in advance!

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# Homework Help: Initial velocity of soccer ball and length of time in the air- projectile motion

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