Physics Group 4 Project Essay Research Paper

Physics Group 4 Project Essay, Research Paper

Physics Group 4

Project ........... After being

set our initial topic of the bath tub, we chose as a group to investigate the

heat lost from a bath tub.. We initially

experimented with ideas such as using different shapes, sizes and materials.. Eventually, we decided that the easiest

option was to investigate how the thickness of a bath tub effects the heat

loss, as well as how conduction, convection (evaporation) and radiation

effected the heat lost from a bath tub and how we could reduce these forms of

heat loss. We chose to use vacuum formed plastic bath tubs as they were the

quickest to build, and we did not want to waste valuble experimenting time

building lots of bath tubs.. The

polyethene plastic also mimicked the material of a real bath tub fairly

successfully.The investigation of energy (heat) lost in different bath

tubs. ........... We began

our investigation by determining the specific heat capacity of water. In order

to do this, we took a known mass of water in an insulated beaker and gave it a

known quantity of energy by using an emersion heater.. We also used an accurate thermometer in order to take the

temperature change in the water.. We

then used the equation: ........... E = mc∆t We then rearranged the formula to give: ........... c = E/m∆t In order to calculate the specific heat capacity of water

(c), we took the known quantities of mass, energy and the change in temperature

and inserted them into the above equation. In order to calculate the energy

given to the water, we used electricity to heat the water, by doing this we

were able to calculate the energy using P = VI.. We measured both the voltage and the current that we used to heat

the water.. We had previously weighed

the water and hence we knew the mass, and the change in temperature we measured

using a thermometer.. Hence we were able

to calculate the following values for the specific heat capacity of water: Test 1 Test 2 Test 3 Average Specific heat capacity of water 4745 4723 4216 4561 ........... The actual

specific heat capacity of water is 4200..

We would expect our results to be lower than this value.. However, the beaker was very well insulated

with a lid and hence little heat would have been lost to the surroundings.. The high values can be explained due to: –

The inaccuracy of the probe thermometer we used.. We later found it was not the most accurate

thermometer available to us.. For the

remainder of our experiments we used a far better digital probe type

thermometer. –

The inaccuracy of the digital ammeters, voltmeters and the

unreliability of the power pack and the immersion heater. –

The impurities in the water which was not deionised.Background to our experiment ........... We

researched the different methods of heat loss and came up with the following

information: Conduction: The mechanism by which heat energy is

transferred through solid materials. In the case of our experiment, the heat

from the water will be transferred to a certain extent through the plastic

walls of the bath tub by conduction. Evaporation: The mechanism by which most energetic molecules

escape from the water surface leaving the less energetic molecules behind.. This means the internal energy of the water

is then lowered and its temperature is decreased. Convection: The mechanism by which fluid .currents., caused

by the differential densities of hot and cold fluids, move.. As the fluid gets .hot. the particles

vibrate more, and therefore expand, become less dense and rise.. These particles then cool, become less dense

and sink. For the purpose of this experiment, I will consider the heat

lost by evaporation and conduction as one and the same thing as they are nearly

impossible to separate in a liquid such as water. Radiation: The mechanism by which energy from the water is

lost to the surroundings by electromagnetic waves.. This occurs even at low temperatures.. The Investigation ........... We began

our experiment by building two vacuum formed bath tubs of different

thicknesses.. We decided that in order

to investigate the effect of thickness as well as the heat loss from

conduction, convection and radiation we would undertake the following

experiments. 1)

We would fill both bath tubs with 700g of water and heat them

up to approximately 42.5 degrees, the temperature of an average bath tub.. We would then measure the heat lost from

both the thick and thin bath tubs in a 45 minute period.. We will record the change in temperature

every five minutes and from this hopefully plot a heat loss curve. 2)

We will then put a lid on the bath tubs to reduce the heat

loss due to evaporation and repeat the same experiment. 3)

We will then put insulation around the bath tubs to reduce the

heat loss due to conduction and repeat the same experiment. 4)

We will the

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