Draw a sketch and also a good FBD to identify the relevant forces doing work. Pay attention to the units and positive or negative value of the quantities 1. A football player pushes a tackling dummy forwards at a constant 0.85 m/'s for 11 m using 7150 J of energy. The tackling dummy has a mass of 120 kg. =) Find the force the football player exerts. b) What is the frictional force the dummy exerts? c) What work is done by friction as the dummy is slid along the field for 11 m? d) Is the mass necessary for this question? If not, what force question could be asked that would require the mass of the dummy? 2. A person pushes on a hockey puck with their stick at an angle so the vertical force is 22 N [down] and the horizontal force is 45 N [forward]. Assume the ice is frictionless a) What is the actual force the hockey player transmits to the puck? b) What is the work done by the person pushing the hockey stick if they push the puck for 3.0 s as it moves with a constant velocity of 22 m/'s [forward]? c) What is the significance of the fact that both the horizontal force and motion are both forwards? 3. You may have seen this question previously but now you will approach it using energy concepts. A pair of sleds weighs 25 kg and experience a frictional force of 25 N. If a dog team applies s 175 N force pulling it 12 m find: a) the work done by friction. b) the work done by the dog team. c) the net work done (using the net force). How does then net work compare to the answers from the previous two parts of the question? d) What form of energy does the frictional force represent? What form of energy does the net force produce? This is an artistic representation This is how physicists draw this situation 4. A 50 kg person is taking a ride on an elevator travelling up at a steady speed of 2.5 m/s. Find the time of the elevator trip if the elevator does 4900 J of work on the person