Metric
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60 miles / hour = 60 * [1 hour / 3600 sec] * [1.6 km/1 mile]*[1000 m / 1 km]
60 miles / hour = 26.67 m/s
By similar methods 75 mph = 33.33 m/s
145 grams = 145 / 1000 = 0.145 kg Why 1000
F = m*(v1 - v2)/ t I'll let you figure out why v2 is minus. Think about which way the ball is going.
F = 0.145 kg (26.67 - (- 33.33) ) / 0.1 second
F = 87 N
English
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m = 0.145 kg * 2.2 = 0.319 pounds (mass)
60 mph = 88 feet per second.
75 mph = 75 * 5280 / 3600 = 110 feet / second
F = 0.319 * (88 - - 110)/0.1
F = 631 poundals.