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pickle37
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I was given a list of equations for projectile motion and two of the equations have the same variables but give different outputs. I don't understand when to use one equation and when to use the other. The equations are:
ay=(vfy-viy)/(delta t)
and
(vfy)^2= (viy)^2 + 2ay(delta t)
I tried using the second equation to solve the following problem but got it wrong. In the book they used the first equation. I see how using the first equation makes sense now, but why is it wrong to use the second equation?
A marble rolls off a table at the horizontal velocity of 1.93 m/s. The tabletop is 76.5 cm above the floor. If air resistance is negligible, determine the velocity at impact.
I solved for (delta t) and got 0.4s. I rearranged the second equation to find (vfy) and tried to solve using (viy)=0m/s, ay= 9.8 m/s^2, and (delta t)= 0.4s . I found (vfy) to be 2.8 m/s when its supposed to be 3.9 m/s
ay=(vfy-viy)/(delta t)
and
(vfy)^2= (viy)^2 + 2ay(delta t)
I tried using the second equation to solve the following problem but got it wrong. In the book they used the first equation. I see how using the first equation makes sense now, but why is it wrong to use the second equation?
A marble rolls off a table at the horizontal velocity of 1.93 m/s. The tabletop is 76.5 cm above the floor. If air resistance is negligible, determine the velocity at impact.
I solved for (delta t) and got 0.4s. I rearranged the second equation to find (vfy) and tried to solve using (viy)=0m/s, ay= 9.8 m/s^2, and (delta t)= 0.4s . I found (vfy) to be 2.8 m/s when its supposed to be 3.9 m/s
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