Physics Flashcards
RP 2:
What is the aim of this practical?
RP 2:
To investigate the effectiveness of different materials as thermal insulators
RP 2:
What equipment does this practical require?
RP 2:
- Smaller beaker (250cm^3)
- Larger beaker (500cm^3)
- Kettle
- Water
- Thermometer
- Rubber bands
- Stopwatch
- Insulating materials
- Cardboard
- Heatproof mat
RP 2:
What is the independent variable in this practical?
RP 2:
Time, t (s)
RP 2:
What is the dependent variable of this practical?
RP 2:
Temperature, T (°C)
RP 2:
What variables should be controlled in this practical?
RP 2:
- Volume of water
- The temperature of the water at the start of the experiment
- The thickness of each material
RP 2:
Outline a method for a suitable experiment to investigate the effectiveness of different insulators:
RP 2:
1) Set up the apparatus by placing a small beaker inside the larger beaker
2) Fill the small beaker with 80 cm^3 boiling water from the kettle
3) Place a piece of cardboard over the beakers as a lid. It should have a hole suitable for a thermometer and place the thermometer through this hole and into the water in the small beaker
4) Record the temperature of the water in the small beaker and start the stopwatch
5) Record the temperature of the water every 2 minutes for 20 minutes, or until the water reaches room temperature
6) Repeat the experiment, each time changing the cardboard for another insulating material (in any order) and also without any insulation at all
RP 2:
What’s the First Step in investigating the effectiveness of thermal insulators?
RP 2:
1)Set up the apparatus by placing a small beaker inside the larger beaker
RP 2:
What’s the Second Step in investigating the effectiveness of thermal insulators?
RP 2:
2)Fill the small beaker with 80 cm^3 boiling water from the kettle
RP 2:
What’s the Third Step in investigating the effectiveness of thermal insulators?
RP 2:
3)Place a piece of cardboard over the beakers as a lid. It should have a hole suitable for a thermometer and place the thermometer through this hole and into the water in the small beaker
RP 2:
What’s the Fourth Step in investigating the effectiveness of thermal insulators?
RP 2:
4)Record the temperature of the water in the small beaker and start the stopwatch
RP 2:
What’s the Fifth Step in investigating the effectiveness of thermal insulators?
RP 2:
5)Record the temperature of the water every 2 minutes for 20 minutes, or until the water reaches room temperature
RP 2:
What’s the Sixth Step in investigating the effectiveness of thermal insulators?
RP 2:
6)Repeat the experiment, each time changing the cardboard for another insulating material (in any order) and also without any insulation at all
RP 2:
How would the results for this experiment be presented?
RP 2:
Plot a graph of temperature against time and draw a curve of best fit
- Plot all the curves for each material on the same axis
RP 2:
What information does the graph display about the rate of energy transfer?
RP 2:
The graphs should show that the temperature falls quickly at high temperature, then more slowly.
This is because:
When water is at a high temperature: there is a greater temperature difference between it and room temperature which creates a high rate of energy transfer
When water is at a low temperature: there is less temperature difference between it and room temperature. This creates a low rate of energy transfer
RP 2 :
Safety Precautions:
RP 2:
- Keep water away from all electrical equipment
- Make sure not to touch the hot water directly
- Run any burns immediately under cold running water for at least 5 minutes
- Do not overfill the kettle
- Place the small beaker inside the large beaker first before pouring water in, since the small beaker will become very hot
- Make sure all the equipment is in the middle of the desk, and not at the end to avoid knocking over the beakers
- Carry out the experiment only whilst standing, in order to react quickly to any spills
RP 2:
How can the accuracy of our readings be improved?
RP 2:
By using a data logger or a thermometer
RP 2:
How can we reduce the effect of random errors?
RP 2:
- Make sure the hole for the thermometer isn’t too big, otherwise the heat will escape through the hole
- Take repeated readings for each insulator
- Read the values on the thermometer at eye level, to avoid parallax error
RP 2:
What else could be tested using this method?
RP 2:
The effectiveness of different thicknesses of the same insulator
RP 2:
Suggest why one beaker is left with no insulation wrapped around it:
RP 2:
To act as a control to compare the temperature drop of the water without vs with insulation
RP 5:
Aim:
RP 5:
To measure the density of various materials.
RP 5:
What 3 categories of material could this experiment be used to measure he density of?
RP 5:
- Regular solids
- Irregular solids
- Liquids
RP 5:
Outline how you would use this method to measure the density of a regular solid object:
RP 5:
1) Use a ruler to measure the length (l), width (w) and height (h) of a steel cube.
2) Place the steel cube on the top pan balance and measure its mass.
3) Calculate the volume of the cube using (l × w × h).
4) Use the measurements to calculate the density of the metal.
5) Use vernier callipers to measure the diameter of the sphere.
6) Place the metal sphere on the top pan balance and measure its mass.
7) Calculate the volume of the sphere using 4/3π(d/2)^3
8) Use the measurements to calculate the density of the metal
RP 5:
Outline how you would use this method to measure the density of an irregular solid object:
RP 5:
1) Place the stone on the top pan balance and measure its mass.
2) Fill the displacement can until the water is level with the bottom of the pipe.
3) Place a measuring cylinder under the pipe ready to collect the displaced water.
4) Carefully drop the stone into the can and wait until no more water runs into the cylinder.
5) Measure the volume of the displaced water.
6) Use the measurements to calculate the density of the stone.
RP 5:
Outline how you would use this method to measure the density of a liquid:
RP 5:
1) Place the measuring cylinder on the top pan balance and measure its mass.
2) Pour 50 cm^3 of water into the measuring cylinder and measure its new mass.
3) Subtract the mass in step 1 from the mass in step 2. This is the mass of 50 cm^3 of water.
4) Use the measurements to calculate the density of the water
RP 5:
What is the formula for density?
RP 5:
Density= mass/volume
RP 5:
What are some sources of experimental error in this practical?
RP 5:
•The top pan balances used by different people may not be identically calibrated
the resolution of the measuring cylinders may be different, causing different values for the volume to be recorded
*The displacement can may not have been set up correctly each time and any additional drops of water would cause some to dribble out of the spout before use
RP 5:
Safety Precautions:
RP 5:
Use a measuring cylinder to collect displaced water and prevent spills
RP 5:
Give the formula for calculating volume of a prism:
RP 5:
Volume= area of face x height
RP 5:
What unit is used for density?
RP 5 :
kg/m^3
RP 5:
How do you convert g/cm^3 to kg/cm^3?
RP 5:
x 1000
RP 5:
How should the displacement can be filled to maximise the accuracy of your results?
RP 5:
Fill the can until water starts to drip out of the spout and into the beaker. Don’t submerge the object until the dripping stops.
