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EN 1o Unit 6: Experimental Physics Study Guide Questions and Answers
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EN 1o Unit 6: Experimental Physics Study Guide Questions and Answers
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Unit 6: Experimental PhysicsTerm Definition
The smallest (measuring) interval (on an
Precision (1 mark)
instrument)
State why the student should take several measurements of the diameter and calculate a
mean. (1 mark)
- To minimize random error/the diameter may not be uniform (1)
Explain one precaution she should take to ensure her measurements are as accurate as
possible. (2 marks)
- Repeat readings and calculate mean (1) to minimize random errors (1)
- Measure several different places and calculate mean (1) to allow for variation in
thickness/length/width of tile (1)
- Check zero error (1) to correct systematic error (1)
When measuring the depth of the water, describe how you would measure it to a
precision of 1mm. (1 mark)
- Use a metre rule in a number of places (1)
One side of the tray is lifted up and dropped, causing a wave to cross the surface of the
water. The wave is reflected from side to side across the surface. The wave takes a time t
to cross the surface once. Describe how you would determine an accurate value of t. (2
marks)
- Measure the time for more than one cross at a time (1)
- Repeat and find mean (1)
The percentage uncertainty of k is 12.8% and the value of k is 6.27. It is suggested that the
value for k is equal to the strength of the Earth’s gravitational field 9.81 Nkg -1. Use your
calculations to discuss whether these results support the suggestion. (2 marks)
- %D = ((9.81 – 6.27)/9.81) × 100 = 36% (1)
- %D (36%) > %U (12.8%) so k ≠ g (1)
State why a micrometer screw gauge is the most appropriate instrument to use to
measure the diameter of the wire. (1 mark)
- Precision of 0.01mm is much less than diameter of wire (1) so will give a small %U
,State one technique the student should use to determine a value for the diameter of the
wire, which is as accurate as possible. (1 mark)
- Check zero error/take multiple readings and find mean (1)
State one precaution she should take when using a micrometer screw gauge to measure
the diameter of a string. (1 mark)
- Check for zero error/avoid squashing the string (1)
Apart from repeating her readings, state one precaution she could take to ensure each
measurement is as accurate as possible when measuring the diameter of a coin. (1 mark)
- Check for zero error/measure diameter at several places (1)
Describe how a student would measure the diameter of a wire of a spring as accurately as
possible. (2 marks)
- Measure the coiled length of spring with calipers and divide by the number of loops (1)
- Repeat and average/measure in different places (1)
A student measures the thickness of a coin using a micrometer screw gauge. She takes
measurements at different points on the coin. Explain why this would make the mean
value for the thickness more accurate. (1 mark)
- Thickness of coins varies/identifies anomalies/enables her to discard anomalies (1)
The value of the density for coin Y is 6900 kgm-3 while for coin X it is 7380 kgm-3. The
percentage uncertainties in the measurements are the same for both coins (1.9%). Use
these measurements to decide if the coins are made from the same material. (2 marks)
- %D = ((7380 – 6900)/7140 = 6.7% (1)
- Total %U = 2 × 1.9% = 3.8% (1)
- Since %D > %U so probably not the same material (1)
Complete the table for each measurement. The dimensions of the slide were
approximately 8cm long, 3cm wide and 1mm thick. (4 marks)
Measurement Instrument Precision of Instrument
Length Metre rule 1mm
Width Calliper 0.1mm
Thickness Micrometer 0.01mm
Others
Masses Balance At least 0.1g
Time Stopwatch 0.01s
Give a reason why a student chose to use a Vernier caliper to measure 28mm and a
micrometer screw gauge to measure 6mm. (1 mark)
- To obtain both measurements to 3 significant figures (1)
Explain why a metre rule is suitable to measure the length of a 300mm sheet side. (1 mark)
- Precision is 1mm giving a small %U of 0.3% (1)
, In order to determine the thickness of a sheet, the student folded it in half five times.
Explain why this technique would make the value for the thickness of the sheet more
precise. (2 marks)
- The mean value of thickness is obtained (1) and measuring a larger thickness gives a
smaller %U (1)
- Since thickness is now greater and instrument precision is the same (1)
- Enables at least 2 significant figures measurement since thickness is now greater than
0.1mm (1)
Describe how the height of a bung, h, should be measured with a calliper. (2 marks)
- Holds top and bottom of bung between jaws (1) perpendicularly
- Repeat at different orientations for mean/do not compress/check for zero error (1)
The percentage uncertainty in the density of the band is 4%. The densities of the band and
bung are 1.16 and 1.52 gcm-3 respectively. Use these values to give a comment on the
suggestion that both the band and the bung are made from the same type of rubber. (2
marks)
- %D = (1.52 - 1.16)/(0.5(1.52+1.16)) × 100 = 27% (1)
- %D > %U so probably not the same rubber (1)
The stopclock has a precision of 0.01s. State what is meant by this. (1 mark)
- The smallest significant figure is 0.01s/measures to the nearest 0.01s (1)
- Notes: When there’s a table of results, the precision is the difference between largest and
smallest values and not the stated value unless if the stated value is smaller
e.g. The precision of the calipers is stated to be 0.01mm but when calculating percentage
uncertainty use 23.96 – 23.86 = 0.05
Explain why a stopclock with a precision of 0.01s is a suitable instrument for this
measurement. (1 mark)
- 0.01s < human reaction time (0.1s)/small percentage uncertainty (1)
She used two set squares and a metre rule to measure the external diameter of the can.
Describe how you would use this apparatus to measure accurately the diameter of a can.
Your description should include a diagram. (2 marks)
The percentage uncertainties in the internal and external volumes are 1% and 2.8%
respectively. The volume of metal was determined by subtracting the internal volume
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