Measurements

Question 1

Measurements must be:

Answer 1

• Valid

- Repeatable and reproducable

Question 2

How are ranges used in uncertainty of a set amount of data?

Answer 2

4 wires of diameter
0.34mm 0.33mm 0.36mm 0.33mm 0.35mm
mean diameter is 0.34
The range of the results is a range of 0.03mm (0.36-0.33)
‘The readings lie within 0.015mm (half the range) of the mean value, which we can round up to 0.02mm’
Therefore diameter can be written 0.34mm +-0.02mm therefore DIAMETER IS ACCURATE TO +-0.02mm

Question 3

Zero error

Answer 3

It is a type of error in which an instrument gives a reading when the true reading at that time is zero

Question 4

Accurate measurement

Answer 4

One that is close to the accepted value

Question 5

Precision

Answer 5

The precision of a measurement is the degree of exactness of the measurement.

Question 6

Micrometer precision

Answer 6

0.01mm

Question 7

What happens to the uncertainty of a measurement of diameter when it is used in Pi d^2 /4 equation?

Answer 7

d is raised to a power of 2, therefore you must times the uncertainty you calculate by 2.

(e. g uncertainty of diameter = 0.01/0.34 x100 = 2.9%)
2x2. 9 = 5.8%