A person measures his or her heart rate by counting the number of beats in 30 s . If 40

Models are particularly useful in relativity and quantum mechanics, where conditions are outside those normally encountered by humans. What is a model?

How does a model differ from a theory?

If two different theories describe experimental observations equally well, can one be said to be more valid than the other (assuming both use accepted rules of logic)?

What determines the validity of a theory?

Certain criteria must be satisfied if a measurement or observation is to be believed. Will the criteria necessarily be as strict for an expected result as for an unexpected result?

Can the validity of a model be limited, or must it be universally valid? How does this compare to the required validity of a theory or a law?

Classical physics is a good approximation to modern physics under certain circumstances. What are they?

When is it necessary to use relativistic quantum mechanics?

Can classical physics be used to accurately describe a satellite moving at a speed of 7500 m/s? Explain why or why not.

Identify some advantages of metric units.

What is the relationship between the accuracy and uncertainty of a measurement?

Prescriptions for vision correction are given in units called diopters (D). Determine the meaning of that unit. Obtain information (perhaps by calling an optometrist or performing an internet search) on the minimum uncertainty with which corrections in diopters are determined and the accuracy with which corrective lenses can be produced. Discuss the sources of uncertainties in both the prescription and accuracy in the manufacture of lenses.

(a) A car speedometer has a 5.0% uncertainty. What is the range of possible speeds when it reads 90 km/h ? (b) Convert this range to miles per hour. (1 km = 0.6214 mi)

An infant's pulse rate is measured to be 130 5 beats/ min. What is the percent uncertainty in this measurement?

(a) Suppose that a person has an average heart rate of 72.0 beats/min. How many beats does he or she have in 2.0 y? (b) In 2.00 y? (c) In 2.000 y?

A can contains 375 mL of soda. How much is left after 308 mL is removed?

State how many significant figures are proper in theresults of the following calculations: (a)(106.7)(98.2) / (46.210)(1.01) (b) (18.7)2(c)1.601019(3712) .

(a) How many significant figures are in the numbers 99 and 100? (b) If the uncertainty in each number is 1, what is the percent uncertainty in each? (c) Which is a more meaningful way to express the accuracy of these two numbers, significant figures or percent uncertainties?

(a) If your speedometer has an uncertainty of 2.0 km/h at a speed of 90 km/h , what is the percent uncertainty? (b) If it has the same percent uncertainty when it reads 60 km/h , what is the range of speeds you could be going?

(a) A person's blood pressure is measured to be 120 2 mm Hg . What is its percent uncertainty? (b) Assuming the same percent uncertainty, what is the uncertainty in a blood pressure measurement of 80 mm Hg?

A person measures his or her heart rate by counting the number of beats in 30 s . If 40 1 beats are counted in 30.0 0.5 s , what is the heart rate and its uncertainty in beats per minute?

What is the area of a circle 3.102 cm in diameter?

If a marathon runner averages 9.5 mi/h, how long does it take him or her to run a 26.22 mi marathon?

A marathon runner completes a 42.188 km course in 2 h , 30 min, and 12 s . There is an uncertainty of 25 m in the distance traveled and an uncertainty of 1 s in the elapsed time. (a) Calculate the percent uncertainty in the distance. (b) Calculate the uncertainty in the elapsed time. (c) What is the average speed in meters per second? (d) What is the muncertainty in the average speed?

The sides of a small rectangular box are measured to be 1.80 0.01 cm , 2.05 0.02 cm, and 3.1 0.1 cm long. Calculate its volume and uncertainty in cubic centimeters.

When non-metric units were used in the United Kingdom, a unit of mass called the pound-mass (lbm) was employed, where 1 lbm = 0.4539 kg . (a) If there is an uncertainty of 0.0001 kg in the pound-mass unit, what is its percent uncertainty? (b) Based on that percent uncertainty, what mass in pound-mass has an uncertainty of 1 kg when converted to kilograms?

The length and width of a rectangular room are measured to be 3.955 0.005 m and 3.050 0.005 m . Calculate the area of the room and its uncertainty in square meters.

A car engine moves a piston with a circular cross section of 7.500 0.002 cm diameter a distance of 3.250 0.001 cm to compress the gas in the cylinder. (a) By what amount is the gas decreased in volume in cubic centimeters? (b) Find the uncertainty in this volume.

How many heartbeats are there in a lifetime?

A generation is about one-third of a lifetime. Approximately how many generations have passed since the year 0 AD?

How many times longer than the mean life of an extremely unstable atomic nucleus is the lifetime of a human? (Hint: The lifetime of an unstable atomic nucleus is on the order of 1022 s .)

Calculate the approximate number of atoms in a bacterium. Assume that the average mass of an atom in the bacterium is ten times the mass of a hydrogen atom. (Hint:The mass of a hydrogen atom is on the order of 1027 kg and the mass of a bacterium is on the order of 1015 kg. )

Approximately how many atoms thick is a cell membrane, assuming all atoms there average about twice the size of a hydrogen atom?

(a) What fraction of Earth's diameter is the greatest ocean depth? (b) The greatest mountain height?

(a) Calculate the number of cells in a hummingbird assuming the mass of an average cell is ten times the mass of a bacterium. (b) Making the same assumption, how many cells are there in a human?

Assuming one nerve impulse must end before another can begin, what is the maximum firing rate of a nerve in impulses per second?