Answer:
1.95 seconds
Explanation:
Use dimensional analysis to convert mph to ft/s.
21 mi/hr × (5280 ft/mi) × (1 hr / 3600 s) = 30.8 ft/s
Convert yards to feet.
20 yards × (3 ft/yd) = 60 ft
Use distance equation to find time.
distance = speed × time
60 ft = 30.8 ft/s × t
t = 1.95 s
