Question
How many significant figures are there in the number 0.0450?
A. 2
B. 3
C. 4
D. 5
Answer/Explanation
Markscheme
B
The first one being that all non-zero numbers are significant. With a 4 and a 5 in the number, we know there are at least 2 significant digits.
Lastly , is that a trailing zero after a decimal is significant. So the 450 is significant. The zeros in front of the decimal are irrelevant.
Therefore, there are 3 significant digits in this number. Please visit below link for more details
IB Physics Unit 1. Measurements and uncertainties- 1.1 Measurements in physics: Study Notes
Question
A student measures the length l and width w of a rectangular table top.
What is the absolute uncertainty of the perimeter of the table top?
A 0.3 cm
B 0.6 cm
C 1.2 cm
D 2.4 cm
Answer/Explanation
Ans: B
If two values are added together then the uncertainties also add .
\(\Lambda y=\Delta a +\Delta b \)
Hence P = w+w+l+l or \(\Delta p= 2 \times \Delta w +2\times\Delta l\) = 2*0.2+2*0.1= 0.6 cm
Two objects undergo an inelastic collision. Which of the following is correct in respect of both the conservation of momentum and the conservation of total energy of the system?
Answer/Explanation
Markscheme
B
Total momentum and total energy of a system always remain conserved.
In inelastic collisions, some of the kinetic energy goes into the heat energy, with total energy and momentum still being conserved
Question
Which of the following is equivalent to a temperature of –100°C?
A. –373 K
B. –173 K
C. 173 K
D. 373 K
Answer/Explanation
Markscheme
C
TºK = (tºC + 273) or tºC = (TK – 273)
Hence –100°C in K is –100+273 = 173K