Physics Chapter 13 - Picture Problems

 Front - Picture & Question Back - Answer 1. This apple peeler is a compound machine. List the simple machines used to make it work. f o l d 1. a) wedge (peels the apple) b) screw (long shaft with threads) c) wheel & axle (shaft holders) d) lever (handle) 2. A roller coaster car is ready to go from the hill on the left to the hill on the right. Will it make it up to the top of the second hill? Why or why not? f o l d 2. NO! It will will loose energy because of rolling resistance (friction) of the wheels against the track and and air resistance of the car moving though the air. 3. A 0.5 kg  frog jumps from the bank over to the lily pad with an acceleration of 3m/s/s. How much force did the frog exert on the bank when it made its jump? f o l d 3.   F=?     m=0.5kg    a=3m/s/s   F = m * a F = 0.5kg * 3m/s/s F = 1.5 N 4. Plants take in what kind of energy and produce what kind of energy? f o l d 4. Plants absorb sunlight and use it  to produce chemical energy through the process of photosysnthesis. 5. 1) What is the mechanical advantage of this inclined plane? 2) How much work is required to move the 72N weight to the top of the ramp? f o l d 5. 1) Wo = 12m        Wi =  6m        MA = ?     MA = Wo / Wi     (Work Output / Work Input)     MA = 12m / 6m     MA = 2 ----------------------------------------------------------------------------- 2) W=?      F=72N       D=6m     W =F * D     W = 72N * 6m     W = 432 joules 6. A machine uses 55 joules of work to lift an 8N object 5 meters. How much energy was expended through heat? f o l d 6.      W=?   F=8N    D=5m W = F * D W = 8N * 5m W = 40 joules 55 joules - 40 joules = 15 joules expended through heat. 7. Describe Potential energy values at W, X, Y, and Z. f o l d 7. W:  High potential energy X: Low potential energy Y: Medium potential energy Z: Low potential energy 8. If the sheet of notebook paper is lying on the table and not moving, are the forces balanced or unbalanced? f o l d 8. BALANCED As long as the notebook paper is NOT moving, the forces are balanced. 9. What type of energy  transformation is pictured here? f o l d 9. Chemical energy converted into heat and light through the process of combustion. 10. What is the mechanical advantage of this pulley system and why? f o l d 10. TWO There are two supporting strands to this pulley system and so the mechanical advantage is two. The rope that the man is holding does not count, since it is just a continuation of one of the supporting strands. 11. What is the mechanical advantage of this pulley system and why? f o l d 11. ONE  This pullley system has only one supporting strand and therefore it has a mechanical advantage of one. 12. What is the mechanical advantage of this pulley system? f o l d 12. TWO  There are two supporting strands, so the mechanical advantage is two. 13. What is the mechanical advantage of this pulley system? f o l d 13. FOUR There are four supporting strands, so the mechanical advantage is four. 14. Consider that the arrows are pointing to the top of a hill. If you took the zigzag route would you do less work? f o l d 14. NO Both paths reach the same final end point -- the top of the hill. Both paths would take the same amount of work, although the zigzag path would be easier for you. Note in the formula W=F * D, the "distance" here is NOT the length of the path, but rather the height of the hill! 15. If this man is NOT able to move the rock, even though he is struggling to move it.... has he done any  WORK? f o l d 15. NO If the rock does not move, no work has been done. 16. The man is holding the bar bell. Is he doing any WORK? f o l d 16. NO If the bar bell is stationary and he is not moving it.... no work has been done. 17. If the arrow represents Work Input (Wi) and the weight of the cart is Work Output (Wo), which is greater, Wi or Wo? f o l d 17. Wo will be greater. If a spring scale were connected at the arrow end of the cart, the reading on the spring scale will always be less than the weight of the cart, unless the ramp is vertical and then they will have the same value. 18. What class of lever are represented by the alligator's jaws and why? NOTE: The fulcrum is located at the blue dot. f o l d 18. THIRD CLASS LEVER Here is why:  A 3rd class lever has the fulcrum on the end, but the force is in the middle. For the alligator's jaws, the muscles that close and open the jaw are in front of the fulcrum. 19. What class of lever are represented by the can opener and why? NOTE: The fulcrum is located at the blue dot. f o l d 19. FIRST CLASS LEVER Here is why: a first class lever is like a seesaw, with the fulcrum in the middle. The can opener has a pointed end on the left, fulcrum further back, and the force is at the other end. 20. What class lever is represented by the spatula and why? NOTE: The fulcrum is located at the blue dot. f o l d 20. SECOND CLASS LEVER Here is why:  The fulcrum on the end means it is a 2nd or 3rd class lever. Since the blue dot is the pivot point (fulcrum) and the force is applied at the end of the lever, it must be a 2nd class lever. 21. What class lever is represented by the horse drawn cart and why? NOTE: The fulcrum is located at the blue dot. f o l d 21. FIRST CLASS LEVER Here is why: Poor horse! They overloaded the end of the lever system so that the weight has more mass than the horse. With the fulcrum in the middle (the wheels) the horse was lifted into the air. This is a classic seesaw ... or ... 1st class lever. 22. Do all four of these pulleys do the same amount of work? f o l d 22. YES Here is why: They all are lifting the same amount of mass. Each pulley system lifts the weight the same distance. Although they force used decreases as you move from left to right, the distance the rope is pulled increases. So, according to the formula for work, W=F*D, they have done the SAME amount of work. 23. If each box weighs 1kg and you move the pallet of boxes 5 meters, how much work have you done? f o l d 23. W = ?     m=12kg    g=9.8m/s/s    d=5m W = m * g * d W = 12kg * 9.8m/s/s * 5m W = 588 joules 24. For this diagram representing a swing, consider that A and C are at the same height. What is the KE value at A, B, & C? f o l d 24. A = KE is low B = KE is high C = KE is low 25. The weight lifter is moving the barbells from the ground to a position over his head. Is he doing WORK? f o l d 25. YES As long as the object is being moved, WORK is being done.