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dealdoe22
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Homework Statement
The position of a particle in meters moving along the x-axis is given by: x=21+22t-6t^2
Calculate the average velocity of the object in m/s during the time interval t=1s to t=3s.
Homework Equations
x=21+22t-6t^2
t=3 ; t=1
v avg. = Xf - Xi/Tf - Ti = Δx/Δt
don't know if this applies but:
instantaneous velocity = dx/dt = -12t+22
The Attempt at a Solution
Hello all. I am a returning student with a Major in Civil Engineering. At the age of 35, it is difficult to remember sometimes what the simple answers are. I know this may seem elementary to some of you but I believe I am over thinking this question. Please help.
My question is which answer is correct for the question asked?
I attempted this 2 different ways and can't decide if one of them is correct or if either of them are correct.
substituting:
x=21+22(3)-6(3)^2
x=33m
x=21+22(1)-6(1)^2
x=37m
then 33-37/3-1 = -2 m/s for velocity avg.
speed = absolute value of velocity = 2 m/s
or
I took the derivative of the initial equation and then substituted to get:
v=-12t+22
v=-12(3)+22=-14
v=-12(1)+22=10
then -14-10/3-1=-12m/s = 12m/s
Any help would be great. Thank you.