Qualification > Math
Additional Math Help HERE ONLY...!
cooldude:
--- Quote from: jellybeans on June 02, 2010, 04:35:52 pm ---HIIII, um, i need help with Q12ii) pleaseeee :)
Thanks :D
i knw you integrate the velocity to get the displacement but what values do you sub in? :o
thanks again. XD
--- End quote ---
ii) integrate a to find v->
v=1.4t-0.3t^2+k
v=0.5, when t=0, thus k=0.5
thus v=1.4t-0.3t^2+0.5
x=0.7t^2-0.1t^3+0.5t
to find the dist u just have to integrate between the limits, 10 and 0, u dont have to worry about the arbitary constant as when we evaluate definite integrals we dont consider it, so now just substitute the value of 10 in the equation for x as substituting 0 wud give the displacement as 0,
x=70-100+5=-25m
jellybeans:
--- Quote from: cooldude on June 02, 2010, 04:42:29 pm ---ii) integrate a to find v->
v=1.4t-0.3t^2+k
v=0.5, when t=0, thus k=0.5
thus v=1.4t-0.3t^2+0.5
x=0.7t^2-0.1t^3+0.5t
to find the dist u just have to integrate between the limits, 10 and 0, u dont have to worry about the arbitary constant as when we evaluate definite integrals we dont consider it, so now just substitute the value of 10 in the equation for x as substituting 0 wud give the displacement as 0,
x=70-100+5=-25m
--- End quote ---
mmm thats what i did in the first place & got the same answer. but the MS had a different answer ... explanation ? ;D hehs
*whats with the 2x7.5 ? :-\
thanks
J.Darren:
--- Quote from: jellybeans on June 02, 2010, 04:35:52 pm ---HIIII, um, i need help with Q12ii) pleaseeee :)
Thanks :D
i knw you integrate the velocity to get the displacement but what values do you sub in? :o
thanks again. XD
--- End quote ---
When you are dealing with displacement question, one must be very careful with the velocity, if between the given time frame, the particle experiences a change in the direction of travel (forwards / backwards), then you must do partial integration.
jellybeans:
--- Quote from: J.Darren on June 02, 2010, 04:48:50 pm ---
When you are dealing with displacement question, one must be very careful with the velocity, if between the given time frame, the particle experiences a change in the direction of travel (forwards / backwards), then you must do partial integration.
--- End quote ---
ohohhh, but why is it 2x7.5? and not just 7.5+25?
cooldude:
--- Quote from: jellybeans on June 02, 2010, 04:45:18 pm ---mmm thats what i did in the first place & got the same answer. but the MS had a different answer ... explanation ? ;D hehs
*whats with the 2x7.5 ? :-\
thanks
--- End quote ---
k sorry, its about the particle travelling 7.5m in the positive direction and then going back thus we multiply by 2 and then add the 25 m in the negative direction to find the total dist travelled, first the particle travels in the positive x direction and travels 7.5 m, and then for the next 5 seconds it travels 7.5 m back to the origin and then another 25 m in the negative x direction, thus a total distance of 7.5+7.5+25=40 m, sorry i misread the q, i thought it was askin the displacement not the distance travelled, neway j darren answered ur q
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