Turn on thread page Beta

mechanics 1 question ....help me plz ..its tomorrow!! watch

    • PS Helper
    Offline

    0
    ReputationRep:
    PS Helper
    (Original post by bluefire)
    what came from where ?? srry but i am really bad at such questions ...cant imagine them , also cant imagine whhat is going to happen tomorrow?!!!
    come'on ....which part didnt you get??
    • Thread Starter
    Offline

    0
    ReputationRep:
    (Original post by kosy91)
    come'on ....which part didnt you get??
    from where did 7i... and -15i and rest of them come from? plz clarofy further so that i could get it !
    Offline

    17
    ReputationRep:
    (Original post by bluefire)
    what came from where ?? srry but i am really bad at such questions ...cant imagine them , also cant imagine whhat is going to happen tomorrow?!!!
    Well, for it to be underneath point A, it has to have the same i component right? Imagine it in your head, point A and another point beneath it. If we are talking coordinates, both points will have the same X coordinate right? Therefore they will both have the same i component.

    Now, you know that at time 7s, it is at ( 0, 0 ) with speed (2i - 3.5j) right?

    So now you just need to know when it will reach below A. So imagine a point at A (7i - 10j), and ANOTHER point at the origin. The point at the origin moves right 2 and down 3.5 every second. Now you want the i components to be the same, so therefore it will take 7/2 s to reach below point A. Which is 3.5 seconds FROM Origin. Now you plus the 7 seconds before to giv you 10.5 seconds altogether

    Now, you dont have to worry about it being north or south. Its going to be south, since the question states that it will.

    GOod?
    • PS Helper
    Offline

    0
    ReputationRep:
    PS Helper
    (Original post by bluefire)
    from where did 7i... and -15i and rest of them come from? plz clarofy further so that i could get it !
    well its just the same thing we did in part c). only difference is that we know u and the position vector it is at and just find t
    • Thread Starter
    Offline

    0
    ReputationRep:
    (Original post by kosy91)
    as for part d)

    for it to be south of A, it must have the same i position.

    therefore, 7i... + 3(-5i + ...) + t(ui + ...)= 7i

    from above you know that u=2, so this gives you 7.5s

    thus, total time is 3 + 7.5= 10.5s
    from where did =7i come from in this ....7i... + 3(-5i + ...) + t(ui + ...)= 7i:confused:
    • PS Helper
    Offline

    0
    ReputationRep:
    PS Helper
    (Original post by bluefire)
    from where did =7i come from in this ....7i... + 3(-5i + ...) + t(ui + ...)= 7i
    at time t seconds, it is south of A. A has position vector of 7i-10j. therefore for P to be south, it could be 7i-12j or 7i-100j....but the point is it has to be 7i
    • Thread Starter
    Offline

    0
    ReputationRep:
    (Original post by kosy91)
    at time t seconds, it is south of A. A has position vector of 7i-10j. therefore for P to be south, it could be 7i-12j or 7i-100j....but the point is it has to be 7i
    i understood a little bit .....but its not a one night thing...i cant master it now...i might get strained and confused for other questions ...now i am going to get a good night sleep !!! in the afternoon its going to be m1 exam time ...do u think i could make it without this basic!!! thanks for all of your help guys!! appreciate it!!
    • PS Helper
    Offline

    0
    ReputationRep:
    PS Helper
    ofcourse you can make it....dont worry....just do your best

    BEST OF LUCK!!!!
    Offline

    17
    ReputationRep:
    (Original post by bluefire)
    i understood a little bit .....but its not a one night thing...i cant master it now...i might get strained and confused for other questions ...now i am going to get a good night sleep !!! in the afternoon its going to be m1 exam time ...do u think i could make it without this basic!!! thanks for all of your help guys!! appreciate it!!
    Didnt you understand my post? >__>
    • Thread Starter
    Offline

    0
    ReputationRep:
    (Original post by kosy91)
    ofcourse you can make it....dont worry....just do your best

    BEST OF LUCK!!!!
    really thnks alot for the encouragement!!! but i doubt it cuz other blunders might happen but i pray that everything goes perfect!! fingers crossed
    • Thread Starter
    Offline

    0
    ReputationRep:
    (Original post by 2710)
    Didnt you understand my post? >__>
    i am sorry but am exhausted right now ...hope you don't mind it ...am sick also {FLU}..but still managed to cover majority of the portion just this thing vectors laft any how i will give it a best shot without it but still hope an easy one turns up!!
    • PS Helper
    Offline

    0
    ReputationRep:
    PS Helper
    (Original post by 2710)
    Didnt you understand my post? >__>
    i liked your idea of visualising the vectors...most people fail to do that
 
 
 
Poll
Do you want your parents to be with you when you collect your A-level results?
Useful resources

Make your revision easier

Maths

Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

Equations

How to use LaTex

Writing equations the easy way

Student revising

Study habits of A* students

Top tips from students who have already aced their exams

Study Planner

Create your own Study Planner

Never miss a deadline again

Polling station sign

Thinking about a maths degree?

Chat with other maths applicants

Can you help? Study help unanswered threads

Groups associated with this forum:

View associated groups

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Write a reply...
Reply
Hide
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.