Exam 4: Forces and Motion in Two and Three Dimensions

A boat moves through the water in a river at a speed of 8 m/s relative to the water. The boat makes a trip downstream and then makes a return trip upstream to the original starting place. Which trip takes less time?

A stone is thrown with an initial speed of 15 m/s at an angle of 53 $\degree$ above the horizontal from the top of a 40-m building. If g = 9.8 m/s² and air resistance is negligible, then what is the magnitude of the vertical velocity component of the rock as it hits the ground?

A plane is moving due north, directly towards its destination. Its airspeed is 200 mph. A constant breeze is blowing from west to east at 60 mph. At what rate is the plane moving north?

Dana uses a rope to pull a box that weighs 300 N across a level surface with constant velocity. The rope makes an angle of 30 $\degree$ above the horizontal and the tension in the rope is 50 N. What is the coefficient of friction?

Two projectiles are launched at 100 m/s, the angle of elevation for the first being 30 $\degree$ and for the second, 60 $\degree$ . Which of the following statements is false?

A bridge that was 8.3 m long has been washed out by the rain several days ago. How fast must a car be going to successfully jump the stream? Although the road is level on both sides of the bridge, the road on the far side is 2.0 m lower than the road on this side.