ENGINEERING MECHANICS cs TEST summer oblem 602 pointe motorb

ENGINEERING MECHANICS cs TEST summer oblem 602 pointe) motorboat traveling at 4 m/s relative to the water attempes to head east but e a 7.0 ms a. What is the resultant velocity of the motorboat? b. If the width of river is 80 meters wide, then bow much time does it take the boat to travel shore? What distance downstream does the boat reach the opposite shore? 7.0 m/s

Solution

The resultant velocity can be found using the Pythagorean theorem. The resultant is the hypotenuse of a right triangle with sides of 4 m/s and 7 m/s. It is

SQRT [ (4 m/s)² + (7 m/s)² ] = 8.06 m/s

Its direction can be determined using a trigonometric function.

Direction = invtan [ (7 m/s) / (4 m/s) ] = 60°

b. The time to cross the river is t = d / v = (80 m) / (4 m/s) = 20 s

c. The distance traveled downstream is d = v • t = (7 m/s) • (20 s) = 140 m