Children's 82745

The children's car has wheels with a radius of 15 cm, and its speed is 36 km/h. How many times does the toy car wheel turn in a minute at this speed?

Correct answer:

n =  636.6

Step-by-step explanation:

$$\begin{gathered} r=15\text{cm}\to \text{m}=15:100\text{m}=0.15\text{m} \\ v=36\text{km/h}\to \text{m/s}=36:3.6\text{m/s}=10\text{m/s} \\ T=1\text{min}\to \text{s}=1\cdot 60\text{s}=60\text{s} \\ o=2\pi \cdot r=2\cdot 3.1416\cdot 0.15\doteq 0.9425\text{m} \\ s=v\cdot T=10\cdot 60=600\text{m} \\ n=s/o=600/0.9425=636.6 \end{gathered}$$

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