1. a 2.0kg wood box slides down a vertical wood wall while you push on it at a 45度 angle. what magnitude of force should you apply to cauce thebox to slide down at a constant speed? 2.you've entered a "slow ski race"where the winner is the skier who takes the longes time to go down a 15度 slope without ever stopping.you need to choose the best wax to apply to your skis.red wax has a coefficient of kinetic friction 0.25,yellow is 0.20,green is 0.15,and blue is 0.10 .having just finished talking physics,you realize that a wax too slippery will cause you to accelerate down the slope and lose the race.but a wax that's too s tickly will cause you to stop and be disquailified.you know that a strong headwind will apply a 50 N horizontal force against you as you ski,and know that your mass is 75kg.which wax do you choose? 3.in one contest at the county fair,a spring-loaded plunger launches a ball at a speed of 3.0m/s form one corner of a smooth,flat board that is tilted up at a 20度 angle.to win,you must make the ball hit a small target at the adjacent corner,2.50m away.at what angle 系他 should you tilt theball launcher? 4. a child in danger of drowning in a river is being carried down-stream by a current that flows uniformly with a speed of 2.0m/s.the child is 200m from the store and 1500m upstream of the boat dock from which the rescue team sets out.if their boat speed i 8.0m/s with respect to the water,at what angle should the pilot leace the shore to go directly to the child? --

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