PHYSICS 1010 Tutorial #1 Solutions
In its investigations, Physics uses physical quantities (length, mass, time, force, power, work, etc). All
these physical quantities are classified in:
•
Fundamental quantities
length, mass, time.
•
Derived quantities
(quantities that can be expressed as a combination of fundamental quantities):
speed, acceleration, force, power, work, etc.
1.1 Standards of Length, Mass, and Time
Length, mass, and time are fundamental physical quantities. Their units are fundamental units in S.I.=
Systeme International (French) of units: meter, kilogram, second.
Practice 1.1.1:
Complete the following table:
Quantity name
Quantity symbol
Unit name
Unit symbol
distance
D,d
meter
m
area
A
meter squared
m
2
volume
V
meter cubed
m
3
time
T, t
second
s
mass
M, m
kilogram
kg
Practice 1.1.2: Conversions
(use the table below):
1.
7 nm =
7×10
-9
m
2.
20 MV = 2.0×10
7
V
3.
0.9 GW = 9×10
8
W
4.
1 h =
60 min = 3600 s
1.3 Dimensional analysis
– is a powerful method used when we want to determine if an expression has
the correct form
Rules
:
•
Physical quantities can be added or subtracted only if they have the same dimensions.
•
The terms on both sides of an equation must have the same dimensions.

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*Sign up*Practice 1.3.1
- Problem 15, page 19
Is the following equation dimensionally correct?
v
final
= v
initial
+ a × x
•
dimension of the left side: L/T
•
dimension of the right side: L/T + L
2
/T
2
•
Conclusion: this equation is dimensionally incorrect
1.5 Conversion of Units
using conversion factors (a conversion factor is a fraction equal to 1).
Practice 1.5.1
1.
Convert 100 cm in ft, using a conversion factor. We know that 1 ft = 30.48 cm.
100 cm × 1ft/30.48 cm = 3.28 ft
2.
Convert 100 km/h in m/s.
100 km/h = 100 km/h × 1h/3600s × 1000m/1km = 27.8 m/s
3.
Convert 0.0840 g/cm3 in kg/m3
4.
A gram is:
A. 10−6 kg
B. 10−3 kg
C. 1 kg
D. 103 kg
E. 106 kg
5.
The SI base unit for mass is:
A. gram B. pound C. kilogram D. ounce E. kilopound
1.7 Significant Figures - important when you do physics labs
Results of experimental observations can often be confusing and/or misleading if care is not taken with
what might seem a rather trivial matter, but actually quite important:
significant figures
.
The number of significant figures in a value is the number of digits it has. Some examples are given in
Table 1.
•
All non-zero digits are significant. However, zeros may or may not count as significant figures.
•
A zero that is placed between two significant digits is always significant.
•
When a zero precedes, or leads nonzero digits, as in the second example, zeros do not count,
serving merely as place holders fixing the proper decimal place (power of ten). Such zeros are
known as "leading zeros."
•
If a decimal point is present, zeros to the right of the last non-zero digit (trailing zeros) are
significant as in the third example.
Significant figures are very important because the experimentally measured values are usually known

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