Express your answers to problems in this section to the correct number of significant figures and proper units. (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?

Solution 19PE: Step 1 of 4 (a) The formula to find the percent uncertainty is, v % uncertainty = v × 100 Here is the speed and is the uncertainty in speed. Comment Step 2 of 4 Substitute 90km/h for vand 2.0km/hfor v % uncertainty = 290 km/h100 = 2.2% Therefore, the percent uncertainty for the speedometer is . Comment