- #1
MechaMZ
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Homework Statement
time-dependent force, [tex]\vec{}F[/tex]= (8.60i - 4.20tj) N (where t is in seconds) is applied to a 2.00 kg object initially at rest.
(a) At what time will the object be moving with a speed of 15.0 m/s?
The Attempt at a Solution
[tex]\vec{F}[/tex] = ma
[tex]\sqrt{8.6^2 + (4.20t)^2}[/tex] = 2a
a = [tex]\sqrt{8.6^2 + (4.20t)^2}[/tex] / 2
vf = vi +at
15 = 0 + [[tex]\sqrt{8.6^2 + (4.20t)^2}[/tex] / 2]t
this should be an easy question but I can't get the correct answer as 2.86s from the equations above, I can't figure out the reason. hope someone could enlighten me