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Mechanics help (M1)

Hi can someone help me with this M1 question

"A particle starts from a point O with an initial velocity of 2m/s and travels along a straight line with constant acceleration 2m/s^2. Two seconds later another particle starts from rest at O and travels along the same line with an acceleration of 6m/s^2. Find how far from O the second particle overtakes the first
(edited 6 years ago)

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Are you sure you have the accelerations copied down correctly as if they both have the same acceleration along the same path and Particle 1 has already started accelerating before particle 2 then I don't see how particle 2 would be able to even overtake it at all.
(edited 6 years ago)
Original post by Rhiannemahey
Hi can someone help me with this M1 question

"A particle starts from a point O with an initial velocity of 2m/s and travels along a straight line with constant acceleration 2m/s^2. Two seconds later another particle starts from rest at O and travels along the same line with an acceleration of 2m/s^2. Find how far from O the second particle overtakes the first


What have you tried so far?

looks like you need to form 2 equations and solve them simultaneously.

you make initial conditions for each particle

and the difficult thing here is reasoning with the time. The question you ask and must find out(cus this is the difficult bit) is, is the time for particle 1 t-2? or is it t+2 or is the time for particle 2 t-2 or is it t+2? once you've found that out you should have an easy time.
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Notnek
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Original post by Rhiannemahey
Hi can someone help me with this M1 question

"A particle starts from a point O with an initial velocity of 2m/s and travels along a straight line with constant acceleration 2m/s^2. Two seconds later another particle starts from rest at O and travels along the same line with an acceleration of 2m/s^2. Find how far from O the second particle overtakes the first

Please check that you posted the question correctly.
Original post by will'o'wisp2
What have you tried so far?

looks like you need to form 2 equations and solve them simultaneously.

you make initial conditions for each particle

and the difficult thing here is reasoning with the time. The question you ask and must find out(cus this is the difficult bit) is, is the time for particle 1 t-2? or is it t+2 or is the time for particle 2 t-2 or is it t+2? once you've found that out you should have an easy time.


I get that for particle 2 the time is t-2 because it is 2 seconds later but how do you start this question?
Original post by Rhiannemahey
I get that for particle 2 the time is t-2 because it is 2 seconds later but how do you start this question?


done some calculations and i get an answer but are you sure the conditions are right?

If the acceleration of p1=p2 but the initial velocity of p1 is 2 and p2 is at rest, how can p2 ever overtake p1?
Original post by S.H.Rahman
Are you sure you have the accelerations copied down correctly as if they both have the same acceleration along the same path and Particle 1 has already started accelerating before particle 2 then I don't see how particle 2 would be able to even overtake it at all.


Oh gosh, I'm so sorry the second particle travels along the same line with an acceleration of 6m/s^2
Original post by Rhiannemahey
I get that for particle 2 the time is t-2 because it is 2 seconds later but how do you start this question?


You want to write down SUVAT for both particles respectively, then you want to equate their displacements and find the time when they're at the same place, and that's the instant when particle 2 will overtake particle 1. Find what the displacement is at this time.
Do the suvat s=ut+at^2 and do the other suvat with where t Is (t-2) then expand then then have them equal each other then solve for T which is where they are both a equal distance from the point
Original post by Hasham123
Do the suvat s=ut+at^2 and do the other suvat with where t Is (t-2) then expand then then have them equal each other then solve for T which is where they are both a equal distance from the point


I have worked out that t=1 and t=6 but what do I do next?
Original post by Rhiannemahey
I have worked out that t=1 and t=6 but what do I do next?


substitute back into original equation
Original post by Rhiannemahey
I have worked out that t=1 and t=6 but what do I do next?


Original post by will'o'wisp2
substitute back into original equation


A missed obvious note is that you want the condition t−2>0t-2>0 to remain true, so t>2t>2 hence you neglect your first solution.
how have you got 2 t values
u(t-2) +a(t-2)^2 =ut+at^2 expand brackets then rearrange to get 1 value for t
Original post by RDKGames
A missed obvious note is that you want the condition t−2>0t-2>0 to remain true, so t>2t>2 hence you neglect your first solution.

ah yes because if t=2 then they've travelled the same distance gotcha, still going ok on the good ol m1 suvat :P
Original post by Hasham123
how have you got 2 t values
u(t-2) +a(t-2)^2 =ut+at^2 expand brackets then rearrange to get 1 value for t


simultaneous equations
Why have you used simaltanius equations they equal the same thing s so you can say they equal each other then rearrange for t
Original post by Hasham123
how have you got 2 t values
u(t-2) +a(t-2)^2 =ut+at^2 expand brackets then rearrange to get 1 value for t


Isn't the formula s=ut + 1/2at^2
Yes sorry about the mistake
Original post by will'o'wisp2
substitute back into original equation


Thank you I got the answer to be 60m is that correct because I don't think it is
Original post by Rhiannemahey
Thank you I got the answer to be 60m is that correct because I don't think it is


How did you get that..?
Original post by Rhiannemahey
Thank you I got the answer to be 60m is that correct because I don't think it is


hmmm.... when i stick 6 into p1, i get 48m from O and i get the same for p2 :/

@RDKGames sort me out fam i can't finish it xD

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