Lab Report

PRE- LAB QUESTIONS 1

1. Is it possible to get an exact measurement without any uncertainty (error)?

No measurement made is ever exact. The accuracy  and precision of a measurement are always limited by the degree of refinement of the apparatus used, by the skill of the observer, and by the basic physics in the experiment. 

2. What is the zero error and the reading uncertainty (error) for

a) a metre rule

The quoted uncertainty of a length measurement using a meter rule is therefore ±1 mm.

b) a vernier caliper

  The zero error for Vervier Caliper is depend on the Scale, it can be 1/10, 1/20 , 1/50 and 1/100 scale. The uncertainty for vernier caliper is 0.1mm.

c) a micrometer

The error is 0.5 x 0.01 mm = 0.005 mm and the uncertainty is 0.01mm.

3. State the number of significant figures for each of the following numbers

a) 17.20 = 4 significant figures

b) 0.0270 = 4 significant figures

c) 12000 = 5 significant figures

d) 3.1400 = 5 significant figures

4. Perform the following calculations and give the answer with the correct significant figures.

a) 23.90 × 3.81 = 91.059

b) 10.27 ÷ 2.8 = 3.668

c) 4.917 × 1.5 × 12.31 = 90.792

5. State two major differences between a systematic and a random error?

i. Random errors in experimental measurements are caused by unknown and unpredictable changes in the experiment while systematic errors in experimental observations usually come from the measuring instruments.

ii.  Systematic errors tend to be consistent in magnitude and/or direction whereas random errors vary in magnitude and direction.

6. Does the laboratory balance measure weight or mass ? explain.

It uses counter weights (either attached one on a scale, or small one to put on the second platter) that would be affected in the same way as the mass to measure if there was a change in the acceleration (i.e. they would work the same on the Moon). 

Weight gages use a calibrated spring, and are affected by dynamic...