Question

a student is recording how fast a toy car can move. the student records a speed of 10 m/s. the student wants to convert meters per second into kilometers per hour in order to know how fast the toy car moves compared to a real car. there are 1,000 meters in a kilometer, 60 seconds in a minute, and 60 minutes in an hour. using dimensional analysis, how fast is the toy car moving in km/hr? 0.01 km/hr 0.0000027 km/hr 36,000,000 km/hr 36 km/hr

Explanation:

Step1: Set up conversion factors

$10\frac{m}{s}\times\frac{1 km}{1000 m}\times\frac{60 s}{1 min}\times\frac{60 min}{1 hr}$

Step2: Cancel out units

The meters and seconds units cancel out, leaving $\frac{10\times60\times60}{1000}\frac{km}{hr}$

Step3: Calculate the result

$\frac{10\times3600}{1000}=\frac{36000}{1000} = 36$ km/hr

Answer:

E. 36 km/hr