Question

(a) If your speedometer has an uncertainty of 4.0 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?

Answer 1

(a) The percent uncertainty is

$$\epsilon=\frac{4}{90}100\%=4.44\%.$$

(b) The range is from (60-4) km/h to (60+4) km\h, or 56 to 64 km\h.