Mechanics: Vectors and Projectiles
Vectors and Projectiles: Audio Guided Solution
Glenda and Harold are attempting to cross a river in a kayak. The river flows due east at 1.9 m/s. Glenda and Harold head the kayak due north and row at 2.4 m/s (relative to the water). The river is 38 m wide at this location.
a. Determine the resultant velocity of the boat - both magnitude and direction.
b. Determine the time for Glenda and Harold to cross the river.
c. How far downstream will the boat be when Glenda and Harold reach the opposite shore?
Audio Guided Solution
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a. 3.1 m/s, 38° east of north (or 52° N of E) (or 52° CCW)
b. 16 s
c. 30. m
Habits of an Effective Problem Solver
- Read the problem carefully and develop a mental picture of the physical situation. If necessary, sketch a simple diagram of the physical situation to help you visualize it.
- Identify the known and unknown quantities in an organized manner. Equate given values to the symbols used to represent the corresponding quantity - e.g., vox = 12.4 m/s, voy = 0.0 m/s, dx = 32.7 m, dy = ???.
- Use physics formulas and conceptual reasoning to plot a strategy for solving for the unknown quantity.
- Identify the appropriate formula(s) to use.
- Perform substitutions and algebraic manipulations in order to solve for the unknown quantity.
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