Conservation of Energy 1. What does "energy being conserved' mean? 2 marks 2. A particular light bulb, converts energy so that every 100J of electrical energy coming in, creates 8J of light energy and 921 of heat energy. a) What would (normally) be considered the "useful energy?" J 1 mark b) What would be the "Energy in?" J 1 mark c) What is the efficiency of this light? Show original equation and steps. 2 marks 3. A roller coaster uses 800 000 J of energy to get to the top of the first hill. During this climb, it gains 500 000 J of potential energy and pauses (velocity = 0) for a fraction of a second at the very top before heading down the other side. A) Calculate the efficiency of the roller coaster during this part of the ride (the climb). 2 marks Our Energy Future 4. What is "renewable energy?" What are the advantages of renewable energy? 2 marks 5. Currently, the majority of our energy is generated using Fossil Fuels. What are the problems with this situation? 2 marks14. Explain [in terms of energy], what is happening in the following track {assuming no friction loss}. 9 marks (k is worth 2 with reasoning explained} a] A to B: is being converted into b} B to C: is being converted into g) At position E, the coaster has less than at G. h} Which position has the greatest potential energy? . i] Which position has the least potential energy? k) In reality {since there is friction loss}, which position has the greatest kinetic energy? . Why? 6. Improving our use of both solar energy and wind energy will depend on the development of batteries. Why are these two energy sources particularly dependent on improving batteries? 2 marks 7. Two people are being pulled up out of the water by a helicopter. The helicopter pulls the two people upwards, who weight a combined 150kg, and lifts them 20 meters. a} Determine the Work done by the helicopter. SHOW ALL YOUR WORK 3 marks b] Is this work turned into Kinetic or Potential energy? 1 mark 8. If you lifted an 80kg rock onto a atbed trailer that is 2.0 meters off the ground. a} What is the work done? Show all your work! 3 marks b] Once the rock is on the flatbed, another worker pushes against the rock with a force of 250M but is not able to move the rock. Calculate how much work was done 2 marks Calculating Energy 9. A 15000kg locomotive is moving at 12 m/s. What is its kinetic energy? 2 marks 10. What is the potential energy of a 0.40 kg ball at a height of 9.2 m? 2 marks 11. A watermelon suspended in the air at 20m and has a potential energy of 1783.61 Calculate the mass of the water in kg to one decimal place 3 marks 12. A skateboarder who weighs 68kg is going down a ramp. At the very bottom of the ramp they have 2400] of kinetic energy. Calculate their speed in mfs to ONE decimal place. MUST SHOW ALL YOUR WORK 3 marks Problem Solving 13. A 2.6 kg rock is dropped from a height of 10 m. With what speed will it strike the ground. Ignore air resistance. Solve to ONE DECIMAL PLACE and SHOW ALL YOUR WORK 3 marks