1 st PHYSICS HOMEWORK

1. 1st PHYSICS HOMEWORK

2. 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

3. 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

4. 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

5. 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

6. 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 9.3x1011g

7. 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

8. 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

9. 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

10. 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

11. 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