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

    16
    ReputationRep:
    Can someone explain what this really is about because from what I have learnt in 2 hours is that u just manipulate the variables to find the rate of something that is increasing or decreasing but I don't get what the point is .

    Name:  1483747035629-1937288554.jpg
Views: 16
Size:  364.8 KB for this question I don't get how the answer is just -kM . Why wouldn't you do something like this Attachment 609096609098

    Thanks
    Attached Images
     
    • Community Assistant
    Offline

    18
    ReputationRep:
    dm/dt is proportional to -M, the minus there as it is a rate of decrease, so it is equal to some multiple of M.

    dm/dt = -kM
    • TSR Support Team
    • Clearing and Applications Advisor
    Offline

    21
    ReputationRep:
    You're overcomplicating it. All this question is asking you to do is to express the problem described in the question using an equation. The question says that the rate of loss of mass of the leaf is proportional to the mass of the leaf. The rate of change of mass of the leaf is \frac{dM}{dt} and since this is proportional to the mass of the leaf, \frac{dM}{dt}=kM. However, since we are talking about the rate of loss of mass of the leaf, the rate of change of the mass of the leaf is negative. So \frac{dM}{dt}=-kM (assuming k>0).
    • TSR Support Team
    • Study Helper
    Offline

    20
    ReputationRep:
    (Original post by coconut64)
    Attachment 609096609098

    Thanks
    It's not clear what you're trying to show in this image. Can you please explain it line by line?
 
 
 
  • 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
    Did TEF Bronze Award affect your UCAS choices?
    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.