Energy Unit assessment

INTRODUCTION:

In the image, Neil deGrasse Tyson holds a bowling ball on a rope against his face and releases it to swing away from him and then back again...but it doesn't come back and smash his nose! We have seen this with Professor Lewin's college class and Bill Nye in his lab.

The graphs show some of the types of energy that are observed in a system like Neil's bowling ball pendulum. Potential, Kinetic and the E stands for Total Energy.

Remember that the Law of Conservation of Energy states that energy can neither be created nor destroyed - only converted from one form of energy to another. This means that a closed system always has the same amount of energy

• - No response is needed -

Energy is always present and can be transferred and/or transformed throughout a system. Choose the answer that best describes the difference between energy transfer and energy transformation. 

• Transfer is sound energy traveling across the room. While transformation is electrical energy changing into light when someone flips a switch. 

• Energy transformation describes what happens when energy is lost and energy transfer represents energy gained. 

• Energy transformation describes what happens when energy is lost and energy transfer represents energy gained. 

• Transformation is sound energy traveling across the room. While transfer is electrical energy changing into light when someone flips a switch. 

In gym class, you have to run laps and get really hot and sweaty. What kind of energy transformation is being described? 

• Potential to thermal energy 

• Kinetic to light energy 

• Potential to kinetic energy 

• Kinetic to thermal energy 

3. Refer to the image. 

You pull back the pendulum and release it. If left alone, what will happen to the energy in the system over time? 

• The pendulum will lose no energy and swing back and forth forever. 

• The pendulum will come to a stop as kinetic energy is transformed into thermal energy due to friction. 

• The pendulum's swing will change direction. 

• The pendulum's swing will get wider. 

Refer to the image, choose the answer that best represents the energy of the pendulum. Note- Your classmate pulls back the pendulum to position A and releases it. The pendulum travels from point A-E and your partner catches it at point E. 

• The kinetic energy decreases as the pendulum moves from point A-C and increases from points C-E. 

• The kinetic energy increases from points A-C and potential energy increases from points C-E. 

• The potential energy increases as the pendulum moves from point A-C and decreases from points C-E. 

• The potential and kinetic energy stay the same as the pendulum moves from positions A-E. 

Refer to the image.

Jessica wants to ensure the pendulum comes as close to her nose without hitting it. Her and her partner Sam, are initially standing at the distances pictured in the diagram. Sam holds the pendulum at position A and releases it. Given that scenario, which statement is true? 

• If Jessica were to back up 2.5 inches, she would not get hit in the nose with the pendulum. 

• Jessica MAY get hit in the nose because the pendulum could swing to an almost equal position on the other side of position B. 

• The pendulum WILL NOT hit Jessica in the nose because she is closer than 24 inches and the pendulum loses energy as it passes by position B. 

Refer to the the image of the pendulum to answer the following question. You and your lab partners are collecting data during an experiment. You raise and release a pendulum, collecting the height of the pendulum during its first full swing cycle (from Point A to Point E and then E back to A). Each member of the group constructs an argument but one is wrong. Choose the INCORRECT argument below.

• If the pendulum continues to swing freely, it will eventually lose momentum and stop swinging due to friction.

• Point B will have a height of nearly/slightly less than 20 cm, Point E will have a height of nearly/slightly less than 50 cm.

• The pendulum makes its first return swing back from Point E towards point A, the pendulum will exceed a height of 50cm.

• There is a cycle of transformation of energy taking place in this system: from potential to kinetic and vice versa.

How does the total energy of this system change as the pendulum is released and swings back and forth?

• The total energy of the system increases when Neil releases the ball, adding energy of motion to the pendulum.

• The total energy of this system does not change, it is only transferred and transformed into different types of energy.

• The total energy of this system does not change, as energy cannot be transferred and transformed into different types of energy.

• The total energy of the system decreases as the ball swings from the highest point to the lowest point.

Refer to the image to answer the following question. While Neil holds the ball (position A), the energy in the system is              _____       energy, but at the bottom of the swing (position C), the energy is mostly    ________ energy.

• 1.  potential/kinetic

• 1. potential/chemical

• 1. kinetic/thermal

• 1. thermal/sound

The image above shows a pendulum starting at point A and swinging towards point C. The pendulum changes direction and swings back through point E and F.

Use this diagram of the pendulum to answer the following question.

Your teacher shows the class the image. Each group argues the point that “energy in the pendulum has changed from the beginning of the demonstration to the end”. Their arguments are below and only one of them is correct. Choose the correct student response below:

• Position A the pendulum has kinetic energy that is transferred to potential energy at position B.

• The pendulum will slow down but continue to swing until someone stops it.

• The pendulum speeds up from positions A-C and slows down from positions D-F.

• As the pendulum moves from position B to C, the potential energy is increasing.