To convert 420 feet per second to miles per hour (mph), we can follow these steps:
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Convert feet per second to miles per second:
- We know that 1 mile = 5,280 feet. \[ \text{miles per second} = \frac{420 \text{ feet}}{5,280 \text{ feet}} = \frac{420}{5280} \text{ miles} \approx 0.0795454545 \text{ miles} \]
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Convert seconds to hours:
- We know that 1 hour = 60 seconds × 60 minutes = 3600 seconds. \[ \text{miles per hour} = \text{miles per second} \times 3600 \text{ seconds/hour} = 0.0795454545 \text{ miles} \times 3600 \text{ seconds/hour} \]
- Performing the multiplication: \[ 0.0795454545 \times 3600 \approx 286.36363636 \text{ mph} \]
Thus, converting 420 feet per second to miles per hour gives approximately:
\[ \boxed{286.3636 \text{ mph}} \]