Pag 1.1

Question 1

How to find g using light gates

Answer 1

1. Connect light gates to a data logger and as close to the electromagnet as possible
2. The position of the lower light gate should be of the lower light gate should be adjusted such that the height is 0.75m measured using the metre ruler
3. Turn on the electromagnet and attach the ball bearing
4. Switch off the electromagnet and not the time taken for the bearing to fall between the light gates as recorded by the data logger
5. Reduce h by 0.05m by moving the lower light gate upwards and repeat the above two steps, reducing h by 0.05m each time down to 0.25m
6. Repeat the experiment twice more to find mean values of t for each h

Question 2

How to calculate g

Answer 2

Plot a graph of 2H against t2 and draw a line of best fit. The gradient of the line of best fit will be g. This is derived using one of the constant acceleration formula
s = ut + 1/2at^2
h = 1/2gt^2
y = mx

Question 3

Evaluate the method for measuring g with light gates

Answer 3

Distance between upper light gate and starting position must be constant so that it reaches the upper light gate with the same speed

Ball bearing should be dense to mitigate the effects of air resistance

To reduce parallax error in measuring height, a ruler can be clamped directly next to the light gates

You could use the light gates to record initial velocity, final velocity and the time taken for the ball bearing to fall between the gates

Question 4

How to find g using a stopwatch

Answer 4

1. Using a meter ruler, measure a height of 1m. Place the soft pad at the bottom of the ruler
2. Hold the tennis ball so the bottom half is at the 1m mark
3. Release the ball and simultaneously switch on the stopwatch and switch it off as soon as it hits the soft pad. Note the time taken for the ball to hit the ground (t) as recorded by the stopwatch
4. Reduce h by 0.05m and repeat the above two steps, reducing h by 0.05m each time down to 0.50m
5. Repeat the experiment twice more to find mean values of t for each value of g

Question 5

Evaluate finding g using a stopwatch

Answer 5

Metre ruler must be perpendicular to the ground, you could use a set square to make sure this is the case.

The tennis ball will experience a large amount of air resistance which may affect your calculation of g, therefore the tennis ball can be swapped out for a ball bearing to improve results

Reaction times will hugely affect the recorded times, making the results less accurate

Question 6

Overall comparison of the two methods

Answer 6

Second method is easier to carry out and require less complex equipment, however it will be far less accurate. Therefore, the initial method is better for calculating a more accurate value of g