# Power Point

```Chapter 1
Branches of Physics
Measuring = units
MASS
[kg]
LENGTH/DISTANCE
[m]
TIME
[s]
What do these have in
common?
Odd one out???
LBS vs. KG
Weight is measured in pounds (USA)
Mass is measured in kilograms
1 kg = 2.20462262 pounds
1 kg = 2.2 lbs
1 lb = 454 g
MASS
50 – 75 kg
MASS
Bumblebee bat – 1.5g – 2.0 g
MASS
Blue whales:
Newborn –
2.5 tons
Avg. 100 – 120
tons
Biggest – 190 tons
CONVERT
1) your weight in lbs to mass in
kg (1 kg = 2.2 lbs)
2) 190 tons to pounds
1 mile = 1.609344 kilometers
1 mile = 1.6 km
1 yard = 0.9144 m
1 foot = 0.3408 m
1m = 3.2808 ft
Football field in meters?
What is the length of a football field in meters?
120 yards
1 yard = 0.9144 m
mph – km / h – m/s
65 mph = 104 km/h
104 km / h
to m/s
104 km = 140,000 m; 1 h = 3600 s
65 mph = 29m/s
km / h – m/s
é km ù 1000 é m ù 10 é m ù
êë h úû = 3600 êë s úû = 36 êë s úû
[km / h]
= [m / s]
3.6
75 km/h =
25 m/s =
120 km/h =
12 m/s =
Scale of the Universe
 A super cool applet
SN you need to remember:
-9
nano
n
-6
micro
m
-3
milli
m
-2
centi
c
10
3
kilo
k
10
6
mega
M
10
10
10
10
Convert, use Scientific Notation
+
BIG ® SMALL Þ BIG(10 )
-
SMALL ® BIG Þ SMALL(10 )
Examples
[cm] ® [m]
-
SMALL ® BIG Þ (10 )
45cm ® ...[m]
-2
-1
45cm = 45 ×10 m = 4.5 ×10 m
Examples
[m] ® [cm]
+
BIG ® SMALL Þ (10 )
45m ® ...[cm]
45m = 45 ×10 cm = 4.5 ×10 cm
2
3
Examples
[ mm] ® [m]
-
SMALL ® BIG Þ (10 )
200 mm ® ...[m]
200 mm = 200 ×10 m = 2 ×10 m
-6
-4
Examples
[m] ® [ mm]
+
BIG ® SMALL Þ (10 )
200m ® ...[ mm]
200m = 200 ×10 mm = 2 ×10 mm
6
8
Practice 1
2.5 days to seconds ________________________________________
3.5 km to mm ______________________________________________
43 cm to km _______________________________________________
22 mg to kg _______________________________________________
671 kg to µg _______________________________________________
8.76 x 107 mW to GW _______________________________________
1.753 x 10-13 s to ps _________________________________________
Practice
The mass of the parasitic
wasp Caraphractus cintus
can be as small as 5x10-6 kg.
What is the mass in
a)g
b)mg
c) µg
PRACTICE
2 dm - … mm
2h 10 min - … s
16 g - … micrograms
0.75 km - … cm
0.675 mg - …g
462 µm - … cm
35 km/h - … m/s
Precision & Sig. Dig.
LAB on Precision
 1) Use the solid 1 m stick and measure the length of the
lab table
 2) Use the 1 m stick marked with dm
 3) Use the 1 m stick marked with cm
 4) Use the actual meter stick to measure the length of
 Write down the results to the maximum precision in each
case.
Sig. Fig.
100 000
100. 00
202 000
0.0050
340 505
0.00505
How many Sig.Figs?
300 000 000 m/s
3.00 ×108 m/s
25.030 °C
0.006 070°C
1.004 J
1.305 20 MHz
Practice
The value of the speed of light is
now known to be 2.997 924 58
×108m/s.Express the speed of
light in the following ways:
a) 3 SF
b) 5 SF
c) 7 SF
# of digits 0.______ (after the
decimal point) = the least
precise
3345.28 + 0.2 = 3345.48 = 3345.5
57.8 – 0.567 = 52.233 = 52.2
Multiplying and Dividing
#SF (result) = the least #SF (A*B)
1.34 x 2300 = 3082 = 3.1103
#SF (result) = the least #SF (A/B)
23967 / 45 = 532.6 =5.3102
Practice
Bicyclists in the Tour de France
reach speeds of 34.0 miles per hour
(mi/h) on flat sections of the road.
What is this speed in a) km/h and b)
m/s - ?
1 mile = 1.61 km
Practice
a) find the sum of 756 g,
37.2 g, 0.83 g, and 2.5 g
b) the quotient 3.2 m/ 3.563 s
c) the product of 5.67 mm ×π
d) 27.54 s - 3.8 s
Density lab
Trig Review
c = a2 + b2
b = csin a
a = ccosa
a = csin b
b = ccos b
æ bö
a = tan ç ÷
è aø
æ aö
b = tan ç ÷
è bø
-1
a
b
c
=
=
sin a sin b sin g
-1
c2 = a2 + b2 - 2ab cos l
Physics Quantities
SCALARS –
magnitude
only
VECTORS –
magnitude
and
direction
Vector vs. Scalar
Velocity
vs.
Displacement
v – scalar;
vs.
Speed
Distance
v - vector
v – vector;
(typed text)
a)
b)
c)
d)
Comparing vectors
Which vectors have the same magnitude?
Which vectors have the same direction?
Which arrows, if any, represent the same vector?
a
b
a+b
a+b
b+a
b+a
Subtracting vectors (+ negative)
a
a-b
a-b
b
b-a
b-a
Subtracting vectors (“fork”)
a
a-b
b
a-b
b-a
b-a
Construct and label a diagram that shows the
vector sum 2A + B. Construct and label a
second diagram that shows B + 2A.
Construct and label a diagram that shows the vector
sum A – B/2. Construct and label a second diagram that
shows B/2 - A.
R = 1600 + 400 = 44.7(km)
-1 æ 40.0 ö
q v = tan ç
= 63.4
÷
è 20.0 ø
R
qv
qv
20.0km
qh
40.0km
æ 20.0 ö
q h = tan ç
= 26.6
÷
è 40.0 ø
-1
Practice (p. 24, #24)
 Vector A has a magnitude of 63 units and
points due west, while vector B has the same
magnitude and points due south. Find the
magnitude and direction of
 (a) A+B and
 (b) A-B .
 Specify the directions relative to due west.
Practice (p. 24, #25)
 (a) Two workers are trying to move a heavy crate. One
pushes on the crate with a force A , which has a magnitude
of 445 newtons and is directed due west. The other pushes
with a force B, which has a magnitude of 325 newtons and
is directed due north. What are the magnitude and
direction of the resultant force A+B applied to the crate?

(b) Suppose that the second worker applies a force - B
instead of . What then are the magnitude and direction of
the resultant force A-B applied to the crate?
 In both cases express the direction relative to due west.
 To add vectors that are not
perpendicular to each other, we
will use components.
 Each vector has vertical and
horizontal components, for
example a has ax and ay
^
Components
3.0km 30 WN
bx
y
2.5km 30 NE
b
by
a
ay
bx = -3.0sin 30 = -1.5(km)
by = 3.0 cos 30 = 2.6(km)
ax
x
ax = 2.5 cos 30 = 2.2(km)
ay = 2.5sin 30 = 1.25(km)
y
b
R
a
x
To find the resultant…
Rx
Ry
R
We need the components
Finding Rx and Ry
y
Rx - ?
Rx = ax + bx
b
Ry - ?
Ry = ay + by
R
R = Rx2 + Ry2
a
x
To find the resultant…
Rx
Rx = ax + bx = 2.2 - 1.5 = 0.7(km)
Ry = ay + by = 1.25 + 2.6 = 3.85(km)
Ry
qv
R
R = Rx2 + Ry2 = 0.49 + 14.8 = 3.9(km)
Direction?
qh
æ Ry ö
q h = tan ç ÷
èR ø
-1
x
æ Rx ö
q v = tan ç ÷
è Ry ø
-1
or 3.9km
20 EN
```

15 cards

11 cards

11 cards

22 cards

17 cards