Physics 1.2 - Measurements And Uncertainties

Explanation
14 billions years  years secs.
If 1 year is converted to seconds, you will get wrong answer A. If only billion years get converted to years, you will get the wrong answer B.

Explanation
Because we have work = force x distance = mass x acceleration x distance. Thus we have, considering an object of 1 kg get moved at for  , then the work will equal to
work =  
= 
= 

Explanation
100 pm= 100pm x

If you calculate 100 m in terms of km, then you will get wrong answer A. If you calculate 100 pm in terms of m, then you will get wrong answer C. If you calculate 1pm in terms of km, you will get wrong answer E.

Explanation
Ampere is the SI base unit for current.

Degree Celsius is not temperature’s SI unit. It should be Kelvin. So A is wrong.

Coulomb is a derived SI unit. It is the unit of charge, which is equivalent to . So C is wrong

Gram is not the base unit. The base unit for mass is kilogram. So D is wrong

Year is not the base unit. The base unit for time is second. So E is wrong

Explanation
We calculate the measurement of the solution by subtracting the remaining solution from the original solution, so we have .
Even if we use subtraction to find the volume of the solution that is poured out, we will add the uncertainties. So the uncertainty of the volume of the solution is 
But it does not make sense to record the measurement of the solution 5.2 mL if the uncertainty is 1 mL. So the volume of the solution is actually .
If you forget to add the uncertainty, you will get wrong answer A. If you subtract the uncertainty, you will get wrong answer D. If you did not change your measurement according to the new uncertainty, you will get wrong answer B.

Explanation
The air flow can decrease or increase the temperature reading, so it is a random error.

If a volumetric cylinder has a bump, then the liquid will be always more than the reading. So it is a systematic error.

If an ammeter has a zero error of 0.1 A, then the reading of the ammeter would be always more than the current in the circuit. So it is a systematic error.

If a student did not read the ruler with his eye directly above the ruler, he will always get a measurement smaller (standing on the left of the ruler), or bigger (standing on the right of the ruler). So it is a systematic error.

Explanation
Because of the decimal point, the zeroes on the right of 2 of choice D do count. So D has 3 significant digits.

Choice A has 4 significant digits.
Choice B has 2 significant digits, because the zeroes on the left do not count
Choice C has 1 significant digit, because the zeroes on the right do not count without a decimal point.