A girl, standing on a bridge, throws a stone vertically downward with an initial velocity of 12.0 m/s, into the river below. If
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Answer:
t = T/4
Explanation:
The power delivered to the mass by the spring is work done by the spring per second.
The work done by the spring is equal to the elastic potential energy stored in the spring.
The maximum energy stored in the spring is at the amplitude of the oscillation.
So the first time the mass reaches to its amplitude can be found by the following equation of motion:
When the mass reaches the amplitude:
because cos(π) = 1.
Using ω = 2π/T,
Answer:
Both balls hit the ground at the same time
Explanation:
Adam drops the ball from rest, so the ball just "<em>falls</em>" in vertical direction, being gravity its only acceleration, for cinematic movements we use that:
In this case we have that gravity is negative, and as Adam drops the ball,
Bob throws the ball horizontally, so the movement will be a <em>parabola</em>, we can divide into horizontal direction, and vertical direction.
But we only need to analize the vertical movement, in wich again the only acceleration is gravity, and compare it with Adam's ball. Again we have that gravity is negative, and as the initial throw is horizontal,
Finally, we have that
where
both for Adam's vertical drop, and for Bob's vertical component of the parabolic throw.
Now, if we put (the origin of the vertical coordinate), we get for both cases that
where we can clear the value for the time t, of the fall, wich will be the same in both cases.
Hence, both balls hit the ground at the same time.