Optional Practical: Hand hot

Introduction

In this practical the heat of the hand will be used to raise the temperature of a small sample of water contained in a test tube. It is important that the area of contact between the hand and tube is always the same so always keep the length of test tube sticking out of the hand constant as shown in the photo.

A temperature sensor will be used to measure the rate of temperature increase of the water; this can also be used as a stirrer to distribute the heat.

Theory

The amount of heat, Q required to raise the temperature of a mass, m of a substance is given by the equation

Q= mcΔT

Where c = specific heat capacity and ΔT is the change in temperature.
The power supplied is the heat added per unit time Q/Δt so

Q/Δt = mc(ΔT/Δt) where (ΔT/Δt) is the rate of increase of temperature.

Using the temperature sensor measure the rate of temperature rise for different masses of water and, using a graphical method, find the heat given by the hand per second.

Cwater = 4180 Jkg-1K-1

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