Will this process change the two sticks in any way? ACTIVITY #7: Smoke Signals Transforming Kinetic Energy Into Thermal Energy   Have you ever seen someone try to start a fire by rubbing two sticks together around some small scraps of wood? The caveman to the left is attempting to start a fire using this process, but doesn’t seem to be having much luck. What does he need to know to accomplish this task? When we rub one stick back-and-forth we give it kinetic energy. To create a fire you need to transform this kinetic energy into heat energy. As the small scraps of wood get hotter and hotter they eventually ignite and you are left with a burning fire. What is heat energy? Will this process change the two sticks in any way?

GOALS: In this lab activity, you will …   GOALS: In this lab activity, you will …  ·        Observe what happens when large quantities of kinetic energy are transformed into heat energy, and this heat energy is concentrated in one part of an object. ·        Recognize that forces are not energy, they are the mechanism by which energy is transferred in a system ·        Look at the role that forces play in the transfer of kinetic energy, and its transformation into heat energy.  (Forces are not energy-mechanism by which energy transferred, random KE is heat energy, HE does not make things move,

Activity Overview: A synopsis of this lesson is as follows…   We will see the transfer and the transformation of kinetic energy into heat energy, this activity bridges the investigations of the energy of large moving objects (balls, cups, bottles, etc.) and the investigations of the kinetic energy of particles, the heat energy. In this activity you will transfer kinetic energy to the particles of a short wooden dowel using a piece of thin rope. The question you will investigate is what will happen to the wooden dowel when its particles receive large amounts of kinetic energy? How will the properties of the dowel change? The particles of wood will not be the only particles receiving energy. The particles that make up the rope will receive energy too. We will be observing the organized kinetic energy of the moving rope and the random kinetic energy of the particles of the rope and wooden dowel

  CONNECTIONS Scientific Content - ·        By pulling on a rope, you give it kinetic energy. Because the entire rope moves as a unit, we can think of this as an organized kinetic energy. The process of delivering energy to the rope involves an energy transfer (from the person to the rope) and an energy transformation (from food energy to kinetic energy) ·        When the rope slides across the wooden dowel, energy is transferred to the wood. This process involves an energy transfer (from the rope to the dowel) and an energy transformation (from the organized kinetic energy of the rope to the disorganized kinetic energy of the particles). When the random (disorganized) kinetic energy of the particles is taken collectively, it is called the heat energy in the object.

  Thus far, we have encountered several forms of energy through our experiments. Ø      The kinetic energy of an object is the energy it has because it is moving. Ø      The gravitational potential energy of an object is the stored energy that it has because it has been lifted up and is above ground level. Ø      Food energy is the energy our body uses to fuel its muscles and the systems within the body that must function to keep us alive.   Ø      The particles that make up objects and substances have kinetic energy and move randomly because of this kinetic energy. The kinetic energy of each particle is too small to be detected, but collectively, the kinetic energies of all the particles can be very large. The combined random kinetic energy of the particles is called heat energy.

One of the problems we have with trying to understand the properties of energy is the simple fact that we cannot see energy. When energy was transferred from golf ball to the cup, we could not actually see anything being transferred. But we could see the cup move, and we assumed it moved because it received energy. The motion of the cup was evidence that energy was transferred. As the cup was sliding to rest on the tabletop, we were told that its kinetic energy was being transferred to the tabletop. Was there any evidence that this was happening? It was clear that the cup was transferring its energy away; otherwise it would not be slowing to rest. But could you detect where the energy was going?   You were told this transferred energy had changed form, and now it was in the form of a random kinetic energy called heat energy. Did you detect the presence of heat energy? Could you see this heat energy make anything move? Did anything feel warmer to you? Your answers to all of these questions are probably NO! Nevertheless, everything you were told thus far is true. It may not seem very believable, but it is all true. In this activity, we are going to look for evidence of heat energy. We will observe what happens if large amounts of heat energy are delivered to a small area.

Gather a 1-meter length of rope and a large wooden   Part A – Using Kinetic Energy to Start a Fire?? . . .or at Least Make Smoke! Gather a 1-meter length of rope and a large wooden dowel rod. Have one student hold the large dowel rod in his hands with his arms outstretched. Have another student wrap the rope around the dowel rod 1 time.   Using long strokes, pull the rope back-and-forth across the large wooden dowel rod.     CAUTION: THE ROPES AND THE WOOD CAN GET VERY HOT DURING THIS ACTIVITY. BE SURE TO AVOID TOUCHING ANY MATERIALS THAT HAVE RECEIVED LARGE QUANTITIES OF HEAT ENERGY. Make observations about the condition of the rope and of the wood. Record your observations in your journal or notebook.   ü     Describe Any Changes You Observed in the Properties of the Wood.  ü    Describe Any Changes You Observed in the Properties of the Jute   Describe Any Changes You Observed in the Properties of the Cotton Rope.        Describe Any Changes You Observed in the Properties of the Nylon Rope. D Describe Any Changes You Observed in the Properties of the Clothes line. 

Investigation Reflection:   1.               1.   Make an energy chain that describes the flow of energy in this activity. Be sure to note each energy transfer and each energy transformation that takes place.                     2. When the cup slides to rest in Activity 3, did either the cup or the tabletop get really hot and start smoking? Use what you know about kinetic energy, heat energy and energy transfer to explain your answer.  4.               3.  Did all of the ropes behave the same in this activity? What differences (if any) did you see, and what could explain these differences?

Forces play a key role in the transfer and the transformation of energy. When one object transfers energy to another object, it does so through the action of a force.. In this activity, the sliding friction force transfers energy from the rope to the wooden dowel, and transforms kinetic energy into heat energy. How much of the kinetic energy is transformed into heat energy depends on the size of the sliding friction force, and how much sliding takes place between the two objects.

3. Are all materials affected by heat energy the same?       1.What happens when large amounts of kinetic energy gets transformed into heat energy and delivered to a small area of an object (such as on the wooden dowel rod)?    2.  How is the heat energy in the rope different from the kinetic energy of the rope?    3. Are all materials affected by heat energy the same?   4. What role does the sliding friction force, between the rope and the wooden dowel rod, play in this activity?