µ IB | Errors

10 quick questions

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10 minutes maximum! (can you do it in 5?)

 

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

Percentage error Fractional error Absolute error
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 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. Whcih numerical answer best completes this sentence?

The exeriment leads to a final fesult for the acceleration of gravity as...

  • A. 11.5 m s-2 ± 1.7 m s-2
  • B. 9.8 m s-2 ± 1.7 m s-2
  • C. 9.8 m s-2 ± 0.2 m s-2
  • D. 11.5 m s-2 ± 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 similiar 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 g ± 0.05
  • B. 72.0 g ± 0.1
  • C. 72.0 g ± 0.5
  • D. 72 g ± 1

 

7. A cube has a side length of 10 cm ± 1 cm. The volume of the cube is

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

 

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

The total mass of both boxes is

  • A. 28 kg ± 2 kg
  • B. 28 kg ± 2.5 kg
  • C. 28 kg ± 3 kg
  • D. 28 kg ± 5 kg

 

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