A soccer goalie kicks a ball. The ball leaves the goalie's foot with an initial upward velocity of 10 meters per second. If the ball is 1.5 meters off the ground when it leaves the goalie's foot, about how many seconds will it take for the ball to hit the ground?

Question

anonymous · Answer

Easy peasy.

You need an equation of motion (a kinematic equation) with all the information you have been given.

1) your initial y value is 1.5 meters

2) your initial velocity is 10 m/s

That is the upward motion as soon as the ball is no longer in contact with the foot.

The only downward motion is the acceleration due to gravity.

So your equation of motion should include BOTH pieces of information:

y(position)=1.5 (this is your initial y) + 10 (this is your initial velocity)t - 4.9(this is half of acceleration due to gravity)t^2 

Simplified: y=1.5+10t-4.9t^2

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anonymous · Answer

PS: Solve the quadratic to find t, the time(s). You will get a negative time and a positive time. Think about them.