Respuesta :
Answer:
t = 6.15 seconds
Step-by-step explanation:
A ball is thrown upward with an initial velocity of 35 meters per second from a cliff that is 30 meters high. The height of the ball is given by the quadratic equation h=-4.9t^2+35t+30 where h is in meters and t in the time in seconds since the ball was thrown, find the time it takes the ball to hit the ground. Round you answer to the nearest tenth of a second.
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h(t) =-4.9t^2+35t+30
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When the ball hits the ground its height is zero.
So, solve -4.9t^2+35t+30 = 0
Use the quadratic formula:
t = [-35 +- sqrt(35^2-4*-4.9*30)]/(2(-4.9))
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t = [-35 +- sqrt(637)]/(-9.8)
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To get a positive solution:
t = [-35-25.24]/(-9.8)
t = 6.15 seconds
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Answer:
The ball hits the ground when h(t) (the height) is equal to 0.
0=-4.9t^2+30t
0=t(-4.9t+30)
t=0 and t=6.1224…
So, the ball hits the ground when it is thrown (0 seconds) and after about 6.1224 seconds.
:)
