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You kick a soccer ball. It reaches a peak height (i.e. the top of its trajectory) of 6 m above the ground. Given this information, which equation would you need to use to directly calculate the time it takes for the ball to travel from its peak height to the ground?

vf = vi + at
v = Δr / Δt
vf^2= vi^2+ 2a(rf - ri)
rf - ri = vit + 0.5at^2

User Ravedave
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Final answer:

To find the time a soccer ball takes to fall from its peak height of 6m to the ground, use the equation ‘rf - ri = vit + 0.5at^2’ with vi=0, a=-9.81 m/s^2, ri=6m, and rf=0m.

Step-by-step explanation:

To calculate the time it takes for a soccer ball to travel from its peak height to the ground, the most appropriate equation to use is the last one: rf - ri = vit + 0.5at^2. In this case, at the peak (rf), the initial velocity (vi) is zero because the ball is momentarily not moving upward or downward. We know the initial height (ri) as 6 m (the peak height), the final position (rf) is the ground level, hence 0 m. The acceleration (a) is due to gravity and is approximately -9.81 m/s^2 (negative because it's directed downward). Here, we're looking to solve for the time (t), thus the equation simplifies to 0 = 0 + 0.5(-9.81)t^2, which we can rearrange to find the time it takes for the ball to hit the ground. Using this equation, you can directly solve for t without needing any other information about the ball's trajectory.

User Nokuap
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