RV-03. (Young & Friedman 11Th Ed. Ex. 3.36) a Railroad Flatcar Is Traveling to the Right

Physics 111 HW5 assigned 13 February 2012

RV-03. (Young & Friedman 11th ed. Ex. 3.36) A railroad flatcar is traveling to the right at a speed of 13.0 m/s relative to an observer standing on the ground. Someone is riding a motor scooter on the flatcar. What is the velocity of the motor scooter relative to the flatcar if it velocity relative to the observer is a) 18.0 m/s to the right? b) 3 m/s to the left? c) 0 m/s?

RV-04. (Young & Friedman 11th ed. Ex. 3.40) An airplane pilot wishes to fly due west. A wind of 80.0 km/h is blowing toward the south. The airspeed of the plane (its speed in still air) is 320.0 km/h. Use a vector diagram to help you answer the following. a) What direction should the pilot head? b) What is the speed of the plane over the ground?

RV-05. (Young & Friedman 11th ed. Prob. 3.85) In a World Cup soccer match, Juan is running due north toward the goal with a speed of 8.00 m/s relative to the ground. A teammate kicks the ball in such a way that it travels at a speed of 12.0 m/s moving in a direction 37.0o E of N relative to the ground. What are the magnitude and direction of the ball’s velocity relative to Juan?

GenFMA-01. A block of ice with mass m sits at rest on a friction-free, frozen lake. A constant force F then acts on the block for a specific time T, resulting in the block having a speed v. a) Start the block at rest again. If the force on and mass of the block are unchanged, but the time the force acts on the block (T) is doubled, what is the new speed (in terms of v)? b) Start the block at rest again. Now the force and time are unchanged from the first trip, but the mass of the block is doubled. What is the speed of the block now (in terms of v)? c) Start the block at rest again. Now the force is doubled, with the mass and time unchanged. What is the speed of the block again? d) Now repeat the trip again, only suppose that the force, time, and mass are all the same. The only thing different now is that the force of gravity is somehow doubled. What is the speed of the block again?

GenFMA-02. A dockworker applies a constant horizontal force of 80.0 N to a block of ice on a smooth horizontal floor. The frictional force is negligible. The block starts from rest and moves 11.0 m in 5.00 s. a) What is the mass of the block of ice?

(over) b) If the worker stops pushing at the end of 5.00 s, how far does the block move in the next 5.00 s?

GenFMA-03. (Young & Friedman 11th ed. Ex. 4.11) A hockey puck with mass 0.160 kg is at rest at x = 0 on a frictionless, horizontal hockey rink. At time t = 0, a player applies a force of 0.250 N to the puck, parallel to the x-axis; he continues to apply this force until t = 2.00s. a) What are the position and speed of the puck at t = 2.00 s? b) If the same force is again applied at t = 5.00s for another 2 seconds, what are the position and speed of the puck at t = 7.00s?

o o GenFMA-04. Two forces, F1 = 9.00 N 60.0 above the +x-axis and F2 = 6.00 N 53.1 below the +x-axis, act on a mass m = 10 kg. a) What are the x and y components of the resultant force? b) What is the magnitude of the resultant force? c) What is the acceleration of the mass?

GenFMA-05. A spaceship with mass 105 kg is at the origin of a coordinate system at t = 0. At t = 0 it has a velocity of 10 m/s in the +x direction. Also at t = 0, a thruster turns on, which applies a force in the +y direction with a magnitude of 8000 N. Find the magnitude and direction of the spaceship’s velocity after this thruster has fired for 20 seconds. Assume the mass of the ship remains constant.

(over)