Hey there! Sign in to join this conversationNew here? Join for free
    • Thread Starter
    Offline

    0
    ReputationRep:
    A, B and C are three points on a straight line such that AB=80m, and BC=60m. A car is travelling with uniform acceleration passes A, B and C at times t=0, t=4s and t=6s, respectively. Modellng the car as a particle find it accelerationand its velocity at A:no:
    • Thread Starter
    Offline

    0
    ReputationRep:
    em...any help wud b appreciateddddddd.....i b stuck on this Q 4 like an hour now..o.O
    • Community Assistant
    Offline

    20
    ReputationRep:
    Community Assistant
    Use the SUVAT equations.

    Assume the car has velocity u at A and acceleration a throughout.

    When t = 0, s = 0.

    When t = 4, s = 80

    When t = 6, s = 140.

    Form and solve some simultaneous equations.
    • Thread Starter
    Offline

    0
    ReputationRep:
    em..im sorry, but i really dont get that
    • Community Assistant
    Offline

    20
    ReputationRep:
    Community Assistant
    Right, protege know the answers and will look after you.

    Do you know the equation s=ut+0.5at^2?
    Offline

    0
    ReputationRep:
    (Original post by swirlwood)
    em..im sorry, but i really dont get that
    You know the 5 SUVAT formulas? If not look in the back of your M1 book. Pick good values to allow you to solve a simultaneous equation. Hint: chose a equation that uses displacement time and acceleration.
    • Thread Starter
    Offline

    0
    ReputationRep:
    ive tryd everythn i can fink of...i jus ned someone 2 possibly gt the ansa 4 me.?
    • Thread Starter
    Offline

    0
    ReputationRep:
    (Original post by Mr M)
    Right, protege know the answers and will look after you.

    Do you know the equation s=ut+0.5at^2?
    yepp i doo =D
    Offline

    0
    ReputationRep:
    (Original post by Pr0tégé)
    You know the 5 SUVAT formulas? If not look in the back of your M1 book. Pick good values to allow you to solve a simultaneous equation. Hint: chose a equation that uses displacement time and acceleration.
    Do that.
    • Thread Starter
    Offline

    0
    ReputationRep:
    (Original post by Pr0tégé)
    Do that.
    ..enm i did-unsuccessful
    Offline

    0
    ReputationRep:
    (Original post by swirlwood)
    ..enm i did-unsuccessful
    You've probably forgotten how to do simultaneous equations. Make it so that when you minus the equations a value (u or a) cancels out.
    Offline

    0
    ReputationRep:
    s=ut+0.5at^2

    Therefore, For AB:

    80=4u+8a (1)

    For AC:

    140=6u+18a (2)

    From equation (1),

    40=2u+4a (multiply (1) by 0.5)
    Therefore, 120=6u+12a (3)

    (2)-(3) gives 20=6a
    a=10/3 metres per second squared

    Therefore substitute that into (1):

    u= 40/3 metres per second

    Also, please use better spelling and grammar in your posts ^^
    Offline

    13
    ReputationRep:
    suvat!
    Offline

    0
    ReputationRep:
    (Original post by malolis)
    s=ut+0.5at^2

    Therefore, For AB:

    80=4u+8a (1)

    For AC:

    140=6u+18a (2)

    From equation (1),

    40=2u+4a (multiply (1) by 0.5)
    Therefore, 120=6u+12a (3)

    (2)-(3) gives 20=6a
    a=10/3 metres per second squared

    Therefore substitute that into (1):

    u= 40/3 metres per second

    Also, please use better spelling and grammar in your posts ^^
    Thanks for telling him/her the answer.
    • Thread Starter
    Offline

    0
    ReputationRep:
    ah thankyou, kind of got that now. thanks a lot...and as for language..sorry but really cant b asked when im stuck and stressed with maths...grr.:eek:
    • Thread Starter
    Offline

    0
    ReputationRep:
    (Original post by malolis)
    s=ut+0.5at^2

    Therefore, For AB:

    80=4u+8a (1)

    For AC:

    140=6u+18a (2)

    From equation (1),

    40=2u+4a (multiply (1) by 0.5)
    Therefore, 120=6u+12a (3)

    (2)-(3) gives 20=6a
    a=10/3 metres per second squared

    Therefore substitute that into (1):

    u= 40/3 metres per second

    Also, please use better spelling and grammar in your posts ^^
    sorry but im confusd with this part :40=2u+4a (multiply (1) by 0.5)
    Therefore, 120=6u+12a (3)
    why multiply by 0.5? if its for the sake of simplification...then why not divide by 4?
    Offline

    0
    ReputationRep:
    (Original post by swirlwood)
    sorry but im confusd with this part :40=2u+4a (multiply (1) by 0.5)
    Therefore, 120=6u+12a (3)
    why multiply by 0.5? if its for the sake of simplification...then why not divide by 4?
    How are you going to cancel a term if you divide by 4? Notice that there is a 6u in (2) and a 6u in (3).
 
 
 
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • Poll
    Would you rather give up salt or pepper?
    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
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • 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.