math

Yes, you can use dimensional analysis to figure out the answer. Dimensional analysis is a way of converting units in one system to equivalent units in another system. In order to convert from miles per hour to feet per second, you need to know that there are 1,760 yards in one mile, and 3 feet in one yard. Start by converting mi/hr to yards/hr: 45 mi/hr x (1 mile/1,760 yards) = 2.5 yards/hr Then convert yards/hr to feet/sec: 2.5 yards/hr x (3 feet/1 yard) x (1 hour/3600 sec) = 0.42 feet/sec