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1 st PHYSICS HOMEWORK

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1st PHYSICS

HOMEWORK

HOW MANY SIG FIGS ?

200

3.002

.00034

.7000

Zeros are place holders

1 sig fig

Zeros are between sig figs

4 sig fig

Zeros are place holders

2 sig fig

Zeros are exact zeros

4 sig fig

HOW MANY SIG FIGS ?

3005

5.600

3000.0

1000

Zeros are between sig figs

4 sig fig

Zeros are exact zeros

4 sig fig

Last zero is exact and others are in between

5 sig fig

Bar makes place holders significant

3 sig fig

Rounding to Sig Figs

670,239.286

700,000

1 sig fig

670,000

Need the bar to make the place holder significant

3 sig fig

670,240

5 sig fig

670,239.3

7 sig fig

1.

1.55 x 106 nm = km

This is just a metric conversion ---- always 2 steps.

One step to the BASE unit, meters:

One step to the desired unit, kilometers:

Start with what

you’re given:

1

km

1x10-9

m

1.55 x 106 nm

x

x

1

nm

1x103

m

3 sig figs

1.55x10-6km

2.

.00000093 Tg = g

This is just a metric conversion ---- always 2 steps.

One step to the BASE unit, grams:

One step to the desired unit, micrograms:

Start with what

you’re given:

1

g

1x1012

g

.00000093Tg

x

x

1

Tg

1x10-6

g

2 sig figs

9.3x1011g

3.

8.5 x 10-20 Ml = ml

This is just a metric conversion ---- always 2 steps.

One step to the BASE unit, liters:

One step to the desired unit, milliliters:

Start with what

you’re given:

1

ml

1x106

l

8.5 x10-20 Ml

x

x

1

Ml

1x10-3

l

2 sig figs

1000 ml

1 l

Or you could use this for last fraction

8.5x10-11 ml

4.

8 gallons = liters

Gallons is an English unit and liters is a metric unit - determine what Metric-English conversion will work (from box at top of homework)

Start with what

you’re given:

4

.94

l

qt

8 gal

x

x

1

gal

1

qt

1 sig figs

30.08 liters

30 liters

5.

5.75 x 1015 s = years

Keep converting to bigger units of time until you get to years:

Start with what

you’re given:

1

days

yr

1

1

1

min

hr

5.75 x1015s

x

x

x

x

hr

60

s

24

min

60

365

days

3 sig figs

1.82x108 yr

6.

500 ml/min = qt/hr

This has 2 dimensions. Convert ml to qt and min to hr

Start with what

you’re given:

ml is on top

Min on bottom

1

500 ml

1x10-3

qt

l

60

min

x

x

x

1

hr

min

.94

l

1

ml

1 sig figs

31.9 qt/hr

30 qt/hr

7.

9 in2 = cm2

Need 2 factors of inches to cancel inches squared

Start with what

you’re given:

2.54

2.54

cm

cm

9 in2

x

x

1

in

1

in

1 sig figs

58.06 cm2

60 cm2