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dhphysics
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Homework Statement
A stone is thrown straight up from the roof of a building with initial speed v0. At the same instant, a second stone is thrown from the roof upward at an angle of 60o with the horizontal and with the same initial speed v0. Which is correct?
both stones hit the ground at the same time and with equal speeds.
the stones hit the ground at different times but with equal speeds.
The stones hit the ground at different times and with different speeds.
both stones hit the ground at the same time but with different speeds.
Homework Equations
vf^2 = vo^2 + 2*a*x
x = vo*t + 1/2*a*t^2
The Attempt at a Solution
For the stone that is straight up, the time from when the stone is thrown to when it gets to the top can be found by using the formula vf^2 = vo^2 + 2*a*x, if vf is 0. Therefore, the time t = v0/g
For the stone thrown at an angle, the y component of the v0 is v0sin60. By using the same formula, the time t = v0sin60/g.
V0sin60/g is smaller than v0/g, so the stone thrown at an angle takes longer to hit the ground. That means the stones hit the ground at different times.
The speeds are also not the same because the v0 for the two stones are not the same.
However, this answer is not correct. Could you point out where the mistake in my reasoning is?
Thanks