Physics Practicals

1) To invetsigate a solid material you will need a block of the material with 2 holes in it (for the heater & thermometer)

2) Measure mass of block. Wrap it in isultaing layer (e.g. thick layer of newspaper) to reduce E transferred from block to surroundings. Insert thermometer and heater

3) Measure intial temp of block and set potential difference of power supply to 10V. Turn on power supply & start stopwatch.

4) Once on, current in circuit does work on heater, transferring E electrically from power supply to heater's thermal E store by heating. Causes material's temp to rise.

5) Take readings of temp & current every 10 mins - current shouldn't change as block heats up

6) Collect 10 readings, turn off p.supply. Calculate power using P=IV. Use E=Pt to calculate how much E was transferred, t = time in seconds since experiment began.

7) If you assume all E supplied to heater is > to block you can plot a graph of E transferred & temp.

8) Find gradient of straight part of graph. This is change in temp divided by change in E. Specific H capacity = 1 divided by ( gradient x mass of block)

9) Can repeat experiment with different materials to compaer SHCs

*to investigate SHC of liquids, place heater and thermometer in an insulated beaker filled with known mass of liquid.

Used to check your masses are a good size before you begin the experiment.

1) Use identical spring to one you'll be testing.

2) Load with masses one at a time up to a total of 5.

3) Measure extension each time you add another mass.

4) Work out increase in extension of spring for each mass.

5) If any cause a BIGGER increase then you've gone past the spring's limit of proportionality

6) If this occurs you'll need to use smaller masses or you won't get enough measurements for a graph.

1) Set up apparatus as shown. Make sure you have plenty of extra masses, then measure mass of each & calculate it's weight using W=mg

2) Measure natural length of spring (when no load is applied) with a mm ruler clamped to stand. Take reading at eye level and add a marker e.g. thin ***** of tape to end of spring (readings then more accurate.)

3) Add mass to spring, allow it to come to rest. Record mass, measure new length of spring. Extension = change in length.

4) Repeat process until you have enough measurements

5) Plot force-extension graph of results. It will only start to curve if limit of proportionality is exceeded.

* to check whether the deformation is elastic or inelastic, you can remove each mass temporarily and check the spring goes back to previous extension.

1) Set up apparatus. Set up trolley so that it holds a piece of card with gap in the middle that will interrupt the signal on the light gate twice. Measure length of each bit of card, input into software, the light gate can now measure the velocity for each bit of card & then work out acceleration.

2) Connect trolley to piece of string that goes over a pulley and is connected on other side to a hook (that you know the mass of & can add more masses to.)

3) Weight of hook & any masses attached will provide accelerating force, equal to mass of hook x acceleration due to gravity.

4) Weight of hook + masses accelerates trolley & masses, so you're investigating acceleration of the system (trolley + masses together.)

5) Mark starting line on table trolley is on, so trolley always travels same distance to light gate.

6) Place trolley on starting line, hold hook so string is taut & release it.

7) Record acceleration measured by L.gate. This is the A of the whole system. Repeat 2 times to get average acceleration.

1) Add masses to trolley one at a time to increase mass of system. Don't add masses to the hook or you'll change the force.

2) Record average acceleration for each mass

Investigating Force:

1) Keep total mass of system the same, but change mass on hook. To do this start with all masses loaded onto trolley & transfer masses to hook one at a time, to increase accelerating force ( weight of hanging masses )

2) Mass of system stays the same as long as you're only transferring masses from the trolley to the hook.

3) Record average acceleration for each force.

* friction between trolley and bench may affect acceleration measurements. Could use an air track ( track which hovers trolley on jets of air) to reduce friction.