Turn on thread page Beta
    • Thread Starter
    Offline

    0
    ReputationRep:
    a model car of mass 4 kg moves in straight line along horizontal ground. the resistance of the car has magnitude 4N.

    i) the car batteries provide a constant power of 20 watts.

    a) calculate the acceleration of the car at that instant when its speed is 2ms^-1 ?

    b) when the car passes the point A, it is moving at a constat speed V ms^-1. show that V=5


    ii) the car continues to move at 5ms^-1 until it reaches B at which point the batteries suddenly fail to provide power.
    a) the car subsequently comes to rest at C. find the distance BC.
    b) the time taken for the car to travel from A to C is 8 s . find the distance AB
    • Thread Starter
    Offline

    0
    ReputationRep:
    i got my i) a) 1.25ms^-2 i duno if thats correct or not but how to do the rest actually ?

    thanks again in advance
    • Wiki Support Team
    Offline

    14
    ReputationRep:
    Wiki Support Team
    It'll be moving at a constant speed when the forces on it are equal. When does this happen?
    Offline

    8
    ReputationRep:
    b)P=Fv
    F=4
    v=20/4=5
    Offline

    8
    ReputationRep:
    ii)a)u=5, v=0
    F=ma => -4=4a
    a=-1

    v^2=u^2 +2as
    0=25 -2s
    s=12.5m
    Offline

    8
    ReputationRep:
    8- time taken from B to C= time from Ato B
    a=(v-u)/t =>t=5s

    from Ato B v is constant
    v=s/t
    5=s/3
    s=15m
    • Thread Starter
    Offline

    0
    ReputationRep:
    (Original post by *bobo*)
    b)P=Fv
    F=4
    v=20/4=5
    haha yeah my bro thought me this (damn how i could forget this simple formulae)
    • Thread Starter
    Offline

    0
    ReputationRep:
    (Original post by *bobo*)
    ii)a)u=5, v=0
    F=ma => -4=4a
    a=-1

    v^2=u^2 +2as
    0=25 -2s
    s=12.5m

    oh yeahhh i forgotten about the friction supposed to be oppostite to the direction of motion....thats why it is -4 rightt???
 
 
 
Reply
Submit reply
Turn on thread page Beta
Updated: October 10, 2006

University open days

  • Heriot-Watt University
    School of Textiles and Design Undergraduate
    Fri, 16 Nov '18
  • University of Roehampton
    All departments Undergraduate
    Sat, 17 Nov '18
  • Edge Hill University
    Faculty of Health and Social Care Undergraduate
    Sat, 17 Nov '18
Poll
Black Friday: Yay or Nay?
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

Equations

Best calculators for A level Maths

Tips on which model to get

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.