A car is traveling at 20 m/s. How fast is it moving in km/hr?

A. 45 km/hr
B. 0.02 km/hr
C. 45 miles/hr
D. 72 km/hr
E. 72,000 km/hr



Answer :

To convert the speed of a car from meters per second (m/s) to kilometers per hour (km/hr), follow these steps:

1. Understand the relationship between meters and kilometers, and seconds and hours:
- 1 kilometer (km) is equal to 1,000 meters (m).
- 1 hour (hr) is equal to 3,600 seconds (s).

2. Convert the speed from meters per second to kilometers per hour:
- To convert from m/s to km/hr, multiply the speed in m/s by the factor that converts meters to kilometers and seconds to hours.

3. Use the conversion factor:
- The conversion factor from m/s to km/hr is 3.6 because
[tex]\[ \text{1 m/s} = \text{1 m} \times \frac{\text{1 km}}{\text{1000 m}} \times \frac{\text{3600 s}}{\text{1 hr}} = 3.6 \text{ km/hr} \][/tex]

4. Calculate the conversion:
- Given speed = 20 m/s
- Therefore,
[tex]\[ 20 \text{ m/s} \times 3.6 = 72 \text{ km/hr} \][/tex]

So, the car is moving at 72 km/hr.

The correct answer is:
- ○ 72 km/hr