Turn on thread page Beta
    • Thread Starter
    Offline

    0
    ReputationRep:
    It says the motion of a particle (position vector) r(t) is:

    r(t) = 2cos(6t)i+2sin(4t)j

    1. It asks me to describe the motion in my own words, so what do I actually have to say?

    Is it going 2cos(6t) in the i and 2sin(4t) in the j direction?

    2. How are the acceleration and r(t) = 2cos(6t)i+2sin(4t)j related?
    Do i just say you differentiate r(t) twice to get the acceleration?
    Offline

    1
    ReputationRep:
    (Original post by rpan161)
    It says the motion of a particle (position vector) r(t) is:

    r(t) = 2cos(6t)i+2sin(4t)j

    1. It asks me to describe the motion in my own words, so what do I actually have to say?

    Is it going 2cos(6t) in the i and 2sin(4t) in the j direction?

    2. How are the acceleration and r(t) = 2cos(6t)i+2sin(4t)j related?
    Do i just say you differentiate r(t) twice to get the acceleration?
    If my memory doesn't fail me that would be some kind of circular/elliptical graph if you plotted it on axis.

    As for the second bit, I think so, at least that's what I'd do (maybe stand back for a bit after you've differentiated twice just to see if there are any obvious comments you can make on it).
    • Thread Starter
    Offline

    0
    ReputationRep:
    Thanks, how would i plot it? like t=0, 1, 2 etc..?
    Offline

    1
    ReputationRep:
    (Original post by rpan161)
    Thanks, how would i plot it? like t=0, 1, 2 etc..?
    I'm sure there's a more efficient way but I can't really remember it at the moment, so try plotting it as you said, just set t=0, 1, 2, 3, ...
    • Thread Starter
    Offline

    0
    ReputationRep:
    hmm okay thanks, i'll see how it goes
    • Study Helper
    Offline

    15
    Study Helper
    If you're going to plot the function, I'd be inclined to use multiples and fractions of pi as the values for t.

    Note: This won't be a trivial circle or ellipse. In fact I'm slightly surprised it's M1, given the difficulty of most of the other M1 questions I've seen on here.
 
 
 
Reply
Submit reply
Turn on thread page Beta
Updated: February 10, 2010
Poll
Cats or dogs?
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.