Two boats, each capable of moving in still water at a constant velocity v = 6 m/

Question

Two boats, each capable of moving in still water at a constant velocity v = 6 m/s, set out to cross a river of width W = 20 m. Boat 1 heads directly across the river while boat 2 is pointed at an angle q = 60 degrees with respect to the shore as shown in the diagram below. The current in the river moves at speed v0 = 2 m/s as shown. The next three questions pertain to this situation. 3) How far downstream (D) is boat 2 when it reaches the other side of the river? D = 7.1 m D = 7.9 m D = 10.0 m D = 14.6 m D = 19.3 m Two projectiles are launched from a cliff of height H = 16m as shown in the diagram below. Projectile 1 is launched with velocity v1 = 12 m/s at an angle q1, where q1 = 35 degrees. Projectile 2 is launched with velocity v2 = 12 m/s at an angle q2, where q2 = 50 degrees. The next two questions pertain to this physical situation. 4) If the projectiles are lauched at the same time, which projectile lands first? Projectile 1 lands first. Projectile 2 lands first. The projectiles land at the same time.

Explanation / Answer

for boat 2 :

V2a = velocity of the boat to cross the river = v Sinn60 = 6 Sin60 = 5.2 m/s

W = width of the river = 20 m

t = time taken by the boat to reach opposite shore = W/V2a = 20/5.2 = 3.85 sec

parallel to river flow ,

V2p = velocity of boat parallel to river flow = v Cos60 + vo = 6 Cos60 + 2 = 5 m/s

Xdownstream = V2p t = 5 (3.85) = 19.3 m

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.