Turn on thread page Beta
    • Thread Starter

    Hey was just wondering if anyone could help me with the question

    The temperature of a room (T) is controlled by a thermostat such that when the temperature falls to 12degrees the heater is turned on until the temperature reaches 18degrees. the room then cools until it reaches 12degrees again.
    time (t) is in minutes

    for t in the interval 10< t < 60

    T = 5 + Ae^(-kt)

    where A and K are constants
    given that T=18 when t=10 and that T=12 when t=60

    i) show that k = 0.0124 to 3 sig figs and find the value of A
    ii) find the rate at which the temp of the room is decreasing when t=20

    cheers for any help

    Put the values in to the given formula and you'll have two equations, re-arrange both for A equals, make the two equations equal to each other (eliminating A) and you should be able to work it out from there.

    ii) Is easy. Just think about it. What do you do to find the rate of change of any formula with respect to a certain variable?
Submit reply
Turn on thread page Beta
Updated: April 14, 2011

University open days

  1. University of Bradford
    University-wide Postgraduate
    Wed, 25 Jul '18
  2. University of Buckingham
    Psychology Taster Tutorial Undergraduate
    Wed, 25 Jul '18
  3. Bournemouth University
    Clearing Campus Visit Undergraduate
    Wed, 1 Aug '18
How are you feeling in the run-up to Results Day 2018?
Useful resources

Make your revision easier


Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here


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