ATAR Notes: Forum
VCE Stuff => VCE Mathematics => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Specialist Mathematics => Topic started by: z1m2v3 on September 16, 2010, 07:22:12 pm
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From MathsQuest Exercise 11F 5a) -
A 2 kg mass initially travelling at 2 m/s is brought to rest by a force F = 40/(t+5)^2 N where t is equal to or greater than 0
Calculate the time at which the body comes to rest.
I know you have to use F = ma and transpose to find acceleration, then integrate that to find velocity, then sub in v(0) = 2 to find c, then make v(t) = 0
However the answer i got was t = -5/3 seconds
What have i done wrong? Thanks.
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That force is a RETARDING force, it is negative. If you do that, you get t = 5.