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In this lesson, we will learn how to identify the precision of measured values in terms of significant figures and how to determine the precision of calculated values.

Q1:

Perform the following calculations and express your answer using the correct number of significant digits.

A woman has two bags weighing 13.5 lb and one bag with a weight of 10.2 lb. What is the total weight of the bags?

The force 𝐹 on an object is equal to its mass 𝑚 multiplied by its acceleration 𝑎 . If a wagon with mass 55 kg accelerates at a rate of 0.0255 m/s^{2}, what is the force on the wagon?

Q2:

A speedometer has an uncertainty of 3.0 km/h at a speed of 98 km/h.

What is the percent uncertainty of the speedometer?

Assuming that the percent uncertainty in the speedometer at 60 km/h is the same as at 98 km/h, what is maximum difference between the speed indicated by the speedometer and the speed that you might be moving at?

Q3:

A person measures his or her heart rate by counting the number of beats in 40 s. 5 0 ± 1 beats are counted in 4 0 . 0 ± 0 . 5 s.

What is the person’s heart rate in beats per minute?

What is the uncertainty in the person’s heart rate, in beats per minute?

Q4:

The sides of a small rectangular box are measured to be cm, cm, and cm long.

Calculate the box’s volume in cubic centimetres.

Calculate the uncertainty in the box’s volume in cubic centimetres.

Q5:

Determine the number of significant figures in the following measurement 0.007.

Determine the number of significant figures in the following measurement 1 4 5 4 0 . 0 0 .

Determine the number of significant figures in the following measurement 8 . 0 × 1 0 .

Determine the number of significant figures in the following measurement 57.0320.

Determine the number of significant figures in the following measurement 600.24.

Q6:

Suppose that a person has an average heart rate of 72.00 beats/min. Consider one year as being equal to 525 600 minutes.

How many beats does he or she have in 1.0 year?

How many beats does he or she have in 1.00 year?

How many beats does he or she have in 1.000 year?

Q7:

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

Q8:

Adam’s mass is 185 lb. State this mass in kg to two significant figure precision.

Q9:

If a marathon runner averages 9.5 mph, how long does it take her to run a 26.22 miles marathon? Give your answer in hours.

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