10 minutes maximum! Can you do it in 5?

1. The thickness of a piece of cardboard is measured as 5 ± 1mm . Which of these gives the correct error as a fraction, a percentage and an absolute error?

 Percentage error Fractional error Absolute error (mm) A 20 2 1 B 20 0.2 1 C 25 5 0.2 D 20 0.2 5

2- 4. A student measures the acceleration of gravity by dropping a lead sphere. The experiments lead to 4 results:

g = 11.4, 11.5, 11.5, 11.6 m s-2

Average = 11.5 m s-2

(The accepted answer is 9.8m s-2 to 2 sig figs).

2. The results above can best be described as

• A. precise and accurate
• B. neither precise nor accurate
• C. accurate but not precise
• D. precise but not accurate

3. The student is asked to write a concise conclusion. Which numerical answer best completes this sentence?

The experiment leads to a final result for the acceleration of gravity as...

• A. 11.5 ± 1.7 m s-2
• B. 9.8 ± 1.7 m s-2
• C. 9.8 ± 0.2 m s-2
• D. 11.5 ± 0.1 m s-2

4. The likely cause for the results above is identified as the stop watch being stopped too quickly, making all the time readings out by a similar margin. This kind of error is called

• A. a random error
• B. a calculation error
• C. a description error
• D. a systematic error

5 A ruler is used to measure the depth of a liquid as shown in the diagram. Unfortunately the student has missed the fact that the ruler has a short piece of plastic before the zero mark. Which of these best describes this error and the consequent effect on the depth reading?

 Type of error Effect on recorded reading A random reading is too low B systematic reading is too low C random reading is too high D systematic reading is too high

6. A digital balance gives a mass reading as shown in the diagram. The mass of the block shown should be recorded as

• A. 72.0 ± 0.05 g
• B. 72.0 ± 0.1 g
• C. 72.0 ± 0.5 g
• D. 72 ± 1 g 7. A cube has a side length of 10 cm ± 1 cm. The volume of the cube is

• A. 1000 ± 3 cm3
• B. 1000 ± 1 cm3
• C. 1000 ± 300 cm3
• D. 1000 ± 100 cm3

8. Box A has a mass of 14 ± 2 kg. Box B has a mass of 24 ± 3 kg.

The total mass of both boxes is

• A. 38 ± 2 kg
• B. 38 ± 2.5 kg
• C. 38 ± 3 kg
• D. 38 ± 5 kg

9&10. A ball rolls down a slope of length 20 ± 2cm in a time of 5 ± 1 s.

9. Which of these correctly states the percentage errors in the length and time readings?

 Length error (%) Time error (%) A 2 1 B 10 20 C 0.1 20 D 10 1

10. The average velocity of the ball is 4cm s-1. The total percentage error in the velocity is

• A. 10%
• B. 20%
• C. 30%
• D. 40%