Question

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П. On a river bank, Point B is 6.0 km downstream from Point A. Two friends must make the round trip from Point A to Point B and then return to Point A. One rows a boat at a constant speed of 8.00 km/h relative to the water, the other walks on the shore at a constant speed of 3.50 km/h. The velocity of the river is 5.0 km/h from A to B. 6. How long does it take the rower to make the round trip? a. 1.71 hr b. 2.46 hr с. 2.10 hr d. 3.43 hr 7. How long does it take the hiker to make the round trip? a. 1.71 hr b. 2.46 hr с. 2.10 hr d. 3.43 hr A river flows due south with a speed of 4.5 m/s. A man steers a motorboat across the river. His motor can push the boat through water at a speed of 7 m/s. Starting on the western shore, he points the nose of his boat due east. The river is 500 m wide. What is his speed relative to the ground? 8. Ть. 3.95 m/s d. 10.3 m/s c. 6.22 m/s a. 8.32 m/s What direction is he moving relative to the ground? 9. d. 17.1° SE b. 40.0 SE c. 21.6 SE a. 32.3° SE 10. How much time is required to cross the river? d. 98.1 s Ь. 71.45 c. 58.9 s a. 170 s 11. How far south of his starting point will he reach the opposite bank? d. 213 m c. 844 m b. 321 m a. 512 m 12. Later, the same boatsman using the same boat and starting again from the western shore wants to reach a point on the opposite bank directly east of his starting point. In which direction should he head (i.e. which direction should he point the nose of his boat)? d. 17.1° NE b. 40.0° NE C. 21.6° NE a. 32.3° NE 13. What is the speed of his boat relative to the ground when he takes this heading? d. 5.36 m/s b. 4.11 m/s c. 7.91 m/s a. 1.97 m/s 14. How long will it take him to cross the river? d. 211s b. 48.1 s c. 93.3 s a. 113 s

Answer 1

Solution - Stokryt Rooer A 6.okm 6 Rower The speed of Rower - 8.00km/h relative to water speed of River - S.Okm/h (AB) Time taken by Rover from AB' is Distanie given as tie Hese effect speed of Rower Distance - 6.0km effective speed (8.00+ 5.00 ) km/h effective speed - 13.0km/h 6 B Thus ti fill = 0.46 hour Time taken by Rower from B A is Distance effective speed of Rower given as

Here distance = 6.0km. effective speed -(8-5) Km/ S - Direction, og Rower & River became - effective speed = 3 km/h opposite } - Thus to go te - 2 hour Thus the time taken for Round trip is given as t- tittel t = (0.46 + 2 ) hour A = 2.46 hour Option (6 2.46 hour is CORRECT A Given that - Distance between point AB = 6.0km speed of hiker = 3.5 km/h Time taken from AB : - Distance Time ti= speed of hell seed of hiker hiker t = 3.5 It = 1.71 hour

since hiker does not walk in water, therefore these is no role of speed of over in this case. The time taken by hikes from B A : Distance to a speed 7 to = 3.5 - Az = 1.71 hour Time taken for round frip 18 it-titt t=(1.71+1.71 hour It = 3.42 hour option(d): 3.43 hour is CORRECT