Name: ___________________________________ Date:__________ Physics & the Sport of Bowling Whether you have rolled a bowling ball or have never set foot in a local bowling center you should be able to use the physical concepts we have been exploring and observe with a careful scientific eye and describe the physics going on during a game. We have talked about motion, forces, energy, heat, and waves. Whether you are aware of them or not all of these physical phenomena can be observed during a simple throw of a bowling ball down the lane. A bit about bowling etiquette: Always wear bowling shoes on the lanes. Please do not cross the black foul line. The lane is oiled and the lane is very slippery. Wait for bowlers on the lanes to your right or left. Be certain you wait until the pinsetting machine has completed its cycle and the sweep bar is raised before rolling the ball. Do not stray from your lane after delivering the ball. Keep food and drinks in designated areas. Try to keep your fun and games to within your own group. Please clean up your area when finished and return balls to the rack. Bowling & Physics Observations Motion: First let’s look at the motional part of bowling, specifically, the ball as it travels down the lane. (We will worry about the pins later.) Throw a few balls down the lane and/or watch others toss the ball down the lane. After you have witnessed the motion of the ball, it is your job to try and answer the following questions. 1. Describe the shape(s) of the path of a ball down the lane. Is the motion straight or curved? Some people will have a straight path, others a hook or curved path depending on how they throw the ball. 2. A bowling lane is 60 feet long, use a stopwatch, to determine the average speed down the lane of a tossed bowling ball. Average Speed=distance/time = 60 ft / 2.5 seconds = 24 ft/s. ( About 18 mph – answers will vary for each person) Name: ___________________________________ Date:__________ 3. Does everyone throw a ball at the same average speed? No. Some throw the ball with a higher average speed, others slower. 4. What is happening to the “speed” of the ball down the lane once it is thrown? Any idea why? The speed appears to be decreasing as the ball travels down the lane. The force of friction will help to slow the ball because it always opposes motion. 5. What is happening to the “velocity” of the ball down the lane once it is thrown? Any idea why? Ah! Many descriptions are possible. The ball’s speed is decreasing therefore the velocity is also decreasing. In addition, if the ball has a curved path down the lane the direction the ball is traveling is also changing. So, the direction and speed may both be changing! 6. Does the ball experience “acceleration” once the ball is thrown down the lane? Why of why not? Yes, any change in velocity is the definition of acceleration. Motion Diagrams: 1. Let’s try and draw a vector diagram of the motion of a bowling ball down the lane. Using the diagram, add your own observations of the ball at various times down the lane. (For example, you can time the ball from the moment it is thrown. Say, it takes 4 seconds for the ball to reach the pins – you could draw an approximation of where you feel the ball is on the lane at 0s, 1s, 2s, 3s, and 4s.) (I did the picture below for a straight throw) 2. To the diagram - add an indication (arrows) of the velocity of the ball at those times. (Velocity vectors are solid arrows) 3. To the diagram - add an indication (arrows) of the acceleration you feel the ball is experiencing down the lane. (Acceleration vectors are dashed) Side View Overhead View Name: ___________________________________ Date:__________ Forces: Now we can begin to ask ourselves questions about why the bowling ball is moving in the ways that we have observed. Let’s try and answer these questions concerning the forces that are in action during the motion of the bowling ball and its interaction with the bowling pins. 1. What “force(s)” are acting on the ball to get it in motion down the lane? (There might be many possible answers for this.) Many good answers are possible. Force of gravity (or weight of the ball), forces applied by the muscles in the bowler’s arm, forces applied by the fingers to impart spin in the ball, muscles in the bowler’s legs to accelerate the ball (and bowler) forward…etc…… 2. Once the ball is rolling down the lane, is there still a force(s) acting on the ball? Sure, some are in balance with other forces ( for example force of gravity downward into the ground toward the Earth’s center and the upward force the lane surface provides – normal force) and others are not. Friction is unbalanced by any other force, therefore the ball experiences an acceleration – “slowing down.” (Friction is the “net Force” causing the ball to slow down) 3. What do these forces acting on the ball cause the ball to do in terms of motion? If there is a “net Force” (such as friction in this case) the ball experiences an acceleration making the ball “slow down.” 4. Once the ball is rolling down the lane, what is the direction of the force(s)? (Think carefully – conceptual pitfall) Since the ball is “slowing down” and a “net Force causes masses to accelerate” – then the acceleration (and therefore frictional force) of the ball is in the opposite velocity friction direction as the velocity of the ball. 5. How does the “mass” of a ball change the action of the forces? The larger the mass, the harder it is for the “forces” to cause a change in the motion (larger mass – smaller acceleration with a given force). 6. Before the ball “hits” the pins, what is the speed of the pins? They are not moving – zero. (They may have been wobbling a bit, but mostly not moving) Name: ___________________________________ Date:__________ 7. Does the ball “hitting” the pins cause the pins to experience a change in velocity? Yes, they are moving with many different speeds in many different directions after the ball hits them. So they were mostly stationary before the ball hits and moving after. 8. Do the pins experience a force when the ball “hits” them? How do you know? Yes. Each pin is a mass. Each pin experienced a change in velocity which we call “acceleration.” When a mass accelerates we say it has experienced a “net force!” Energy: Energy is everywhere - we just have to identify the forms of energy and when and how it transfers between energy types. 1. Does the rolling bowling ball have “energy?” If so, what kind of energy? Yes, kinetic energy of motion. 2. Where did the energy the ball has moving down the lane come from? What is this type of energy? Bowlers “raise” the ball upward above the lane before throwing it. This increases the ball’s gravitational potential energy. The bowler then drops it into a swing and lowers it to the lane surface converting the potential energy of position to kinetic energy of motion. (Some bowlers will also add some energy by using the muscles of the arm and legs as well…… ) 3. Does every throw of a bowling ball have the same energy? Why or why not? No, a faster ball will have more kinetic energy than a slower ball traveling down the lane. 4. Do the pins have any easily observable kinetic energy before the ball hits them? Why or why not? No, the pins are stationary. No motion – no kinetic energy. (Why did I say “easily observable?” – Well, the pins do have a temperature – the nanoscale particles that make up the solid wood of the pins will be jiggling with some motion.) 5. After the ball hits the pins, do the pins have any kinetic energy? How do you know? Yes, clearly the pins are moving around after the bowling ball hits them. Moving pins means they have kinetic energy that is easy to see. Name: ___________________________________ Date:__________ 6. If we compared the total amount energy of the bowling ball before it hits the pins to the total amount of energy of the pins and ball after it hits the pins what would we find? Upon what principle do you base your conclusion? The total amount of energy before the ball hits the pins will be equal to the total amount of energy after the collision. We just need to be careful to identify all the energy amounts and types before and after the collision. (….energy of the ball before and after, energy types of the pins before and after, energy in the “sound” waves the collision creates…etc…). This is the Law of Conservation of Energy. 7. Can you identify any time during the motion of the bowling ball down the lane and/or when it hits the pins where we might say the “heat and/or temperature” of an object changed? (Hint: think friction and/or kinetic energy.) Temperature is based on the “average kinetic energy” of all the pieces (molecules, atoms, etc) in a substance. So, in a sense, anytime there is a “change in the kinetic energy” of something you are “changing the temperature.” The pins have a “change in kinetic energy.” The pins are not moving around much before the collision, but after they are moving around a lot more. The pins as a collection of particles could be said to have experienced a temperature change. Waves: The periodic motion of waves is also going on during the game. In fact, it is being sensed by a way we observe the game as it happens. 1. Do you hear anything during a throw of the ball down the lane? What? “Thunk” of the ball hitting the alley. “Rumble” of the ball rolling on the lane….…. “Hip-Hip-Hooray” of the bowler celebrating a strike! 2. Do you hear anything during the collision between the ball and pins? What? “KaaPow” of the ball hitting the pins. “Crash” of the pins hitting each other. I observe “sounds.” Name: ___________________________________ Date:__________ 3. Explain, how you can “hear” these events? Does it have anything to do with waves? Some of the energy during the bowling ball’s collision with the pins is transferred to air molecules near the collision causing them to vibrate. This disturbance in the air molecules travels outward as a longitudinal sound wave to the bowler’s ears so that she “hears” the sound of the “KaaPow.” 4. Does it take “energy” to hear these “sounds?” Why or why not? Yes, vibrations, oscillations, waves, depend on something moving – therefore kinetic energy of motion is involved in the process. 5. Where does this energy come from? Somewhere else. (Not trying to be coy). Energy is neither created nor destroyed, so any energy comes from somewhere else by changing form or being transferred from place to place and process to process. The energy in question creating the sound came from the kinetic energy of the ball which came from the potential energy the bowler gave the ball by lifting it, but the bowler ate some food earlier in the day to store energy to lift the ball, the food eaten got the energy from………… this list goes forever…… Conceptual Summary Simply, the concepts and physical phenomena that science (physics) tries to explain are going on around us all the time. In a simple game of bowling, we can witness all types of situations that deal with motion, speed, velocity, acceleration, vectors, forces, kinetic and potential energy, conservation of energy, heat, and waves. I hope this little activity, can help inspire in you a new way to look at every day life and “see” the physics behind the observations. Science is going on all around us and we certainly use it pragmatically everyday (sometimes in a formal mathematical way) just living our lives.