Ranboo oobnar have a good day
This is a perfect problem to use positive and negative velocities.
Let's call the positive direction the direction that points UP.
Then the negative direction is the one that points down.
The acceleration of gravity on Earth is 9.8 m/s² down. That means
that any object with no forces on it except gravity gains 9.8 m/s of
speed downward every second.
OK. Ready to go to work:
The ball's initial velocity is +(up)20.0 m/s .
Every second after the toss, the ball has -(down)9.8 m/s more velocity.
The ball's velocity after 3 seconds is
+20 + 3(-9.8) =
20 - 29.4 = - 9.4 m/s .
That means it's velocity at that time is 9.4 m/s pointing down.
The time measured is 25 seconds. The error in the measurement is 0.2 seconds. The % error is therefore
(0.2/25)x100 = 0.8%.
The period of one oscillation is 25/20=1.25 seconds. The error in the period is 0.8/100 x 1.25 = 0.01 second.
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ie period = 1.25 +/- 0.01 s.
I hope my answer has come to your help. Thank you for posting your question here in Brainly.
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