Module 1: PAG's Flashcards
PAG 1.1
What are the 2 methods to calculate acceleration due to gravity?
- Dropping a tennis ball and timing using a stopwatch
- Dropping a ball bearing through a light gate to determine final velocity
PAG 1.1 A
What equipment is required for the first method of calculating the acceleration due to gravity?
- Tennis Ball
- Stopwatch
- Metre Rule
PAG 1.1 A
What is the first method for calculating acceleration due to gravity?
1) Secure the meter rule touching and perpendicular to the ground against a wall
2) Hold the tennis ball so that the bottom of the ball is against the 0.5m mark
3) Release the ball and simultaneously press start on the stopwatch. Immediately stop the stopwatch when the tennis ball touches the ground
4) Repeat step 3 2 more times and calculate a mean average time for the tennis ball to fall
5) Repeat steps 2-4 10 more times, increasing the drop height by 0.05m each time.
6) Record results in appropriate table and plot a graph of 2h (2 x drop height) against t² (drop time squared) and draw a line of best fit
7) Calculate g by calculating the gradient of your line of best fit
PAG 1.1 A
What are the variables for the first method of calculating acceleration due to gravity?
Independent: Drop Height
Dependent: Drop Time
Control: Ball Used, Stopwatch Used, Person Timing
PAG 1.1 A
What may affect the accuracy of the results of the first method of calculating acceleration due to gravity?
- The metre rule must be kept perpendicular to the ground
- The tennis ball may experience large amounts of air resistance
- The reaction time of the person with the stopwatch may affect the results
PAG 1.1 A
Why is a graph of 2h against t^2 plotted in the first method of calculating acceleration due to gravity?
s = ut + 0.5at^2
h = 0.5gt^2
2h = g t^2
(the gradient is equal to acceleration due to gravity)
PAG 1.1 B
What equipment is required for the second method of calculating the acceleration due to gravity?
- Clamp and Stand
- Metre Rule
- Light Gate
- Data Logger
- Digital Vernier Calliper
- Ball Bearing
PAG 1.1 B
What is the second method for calculating acceleration due to gravity?
1) Set up the equipment as shown in the diagram, ensuring the light gate is in line with the 0 mark on the metre rule
2) Measure the diameter at the centre of the ball bearing using the digital vernier calliper
3) Input this information into the data logger, selecting a single interrupt card and velocity
4) Hold the ball bearing so that the bottom is on the 0.5m mark
5) Drop the ball bearing so that the centre falls directly through the light gate
6) Repeat steps 4-5 2 more times and calcualte a mean average final velocity
7) Repeat steps 4-6 10 more times, increasing the drop height by 0.05m each time
8) Recrod results in appropriate table and plot a graph of v^2 (final velocity squared) against 2h (2 x drop height) and draw a line of best fit
9) Calculate g by calculating the gradient of your line of best fit
PAG 1.1 B
What are the variables for the second method of calculating acceleration due to gravity?
Independent: Drop height
Dependent: Final Velocity
Control: Ball used, centre of ball should always be dropped through light gate (not edge), person dropping ball
PAG 1.1 B
What may affect the accuracy of the results of the second method of calculating acceleration due to gravity?
- The metre rule must be kept perpendicular to the ground
- The small ball bearing may not fall directly through the light gate, therefore the cntre will not pass through the light gate causing the velocity recorded to be incorrect by a large margin
PAG 1.1 B
Why is a graph of v^2 against 2s plotted in the second method of calculating acceleration due to gravity?
v^2 - u^2 = 2as
v^2 = a2s
v^2 = g 2s
(the gradient is equal to acceleration due to gravity)
ALL PAG’s
What are important things which should not be forgotten when writing a method in order to achieve full marks?
- Variables
- Measure using a ……….
ALL PAG’s
When should you draw a graph to calculate a value rather than using an equation?
Whenever a range of measurements are used to calculate the same value, plot a graph where the value is the gradient of the line of best fit. This will produce much more accurate results than using an equation and a single value. Examples include calculating g and calculating internal resistance
PAG 3.4
What equipment is required for determining the internal resistance of a cell?
- 1.5V standard cell
- Switch
- Ammeter
- Voltmeter
- Variable Resistor
- Fixed Resistor
PAG 3.4
What is the method for determining the internal resistance of a cell?
- Build the circuit shown in the diagram, ensuring the switch is open during assembly
- Set the variable resistor to its highest resistance setting
- Close the switch
- Record the current in the circuit and measure the pd across the terminals of the cell
- Open the switch
- Use the variale resistor to alter the current and repeat steps 3-5 for at least 6 different currents
- Plot a graph of terminal pd against current
- Calculate the internal resistance by multiplying the gradient of the line by -1
Why is a graph of Terminal PD against current plotted when determining the internal resistance of a cell?
- The gradient is equal to -(internal resistance)
- The y intercept is equal to the emf of the cell
