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

    15
    ReputationRep:
    A ball is projected from a point on the horizontal ground. The speed of projection is 30ms-1, greatest height reached is 20m. Assuming no air resistance, find angle of projection above horizontal.
    - And it also goes on to say, find the speed of the ball as it passes through highest point. ) - how can it past through the height-est point

    i tried using V=u+at, i ended up with t=30sinX/9.8 then i tried to find t for the horizontal, which i got t=x/30cosx, equating both (T)
    and solving by simultaneous equations doesn't help.
    Online

    20
    ReputationRep:
    at the highest point the vertical component of velocity is zero... so u2 + 2as = 0

    here u is the initial vertical component of velocity = Vsinθ = 30sinθ

    a = -9.8 ms-2

    s = height = 20 m.
    • Thread Starter
    Offline

    15
    ReputationRep:
    (Original post by the bear)
    at the highest point the vertical component of velocity is zero... so u2 + 2as = 0

    here u is the initial vertical component of velocity = Vsinθ = 30sinθ

    a = -9.8 ms-2

    s = height = 20 m.
    yh and then i used the equation v=u+at, t=\dfrac{30sin \theta}{9.8} for vertical

    i guess i should substitute this into s=ut+ 1/2 at^2
    Online

    20
    ReputationRep:
    (Original post by joyoustele)
    yh and then i used the equation v=u+at, t=\dfrac{30sin \theta}{9.8} for vertical

    i guess i should substitute this into s=ut+ 1/2 at^2
    if you know t then you can use those... my version does not need t.
    • Thread Starter
    Offline

    15
    ReputationRep:
    (Original post by the bear)
    at the highest point the vertical component of velocity is zero... so u2 + 2as = 0

    here u is the initial vertical component of velocity = Vsinθ = 30sinθ

    a = -9.8 ms-2

    s = height = 20 m.
    Oh i see, that is a more simple way of doing it. Thank you
    Online

    20
    ReputationRep:
    (Original post by joyoustele)
    Oh i see, that is a more simple way of doing it. Thank you
    your method works fine, and quite often you need to know t at the top anyway.
 
 
 
  • 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
    Will you be richer or poorer than your parents?
    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

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