What important physics idea is this question targeting?
This examines if students can apply and interpret equations for gravitational potential energy (PE = mgh). (I)
This primarily examines whether or not students understand the conservation of energy implies that energy in this scenario is basically conserved. (C)
This examines whether students can use graphical information to determine energy in a given scenario. (V)
Which answer best describes what student A's response indicates about their physics understanding?
The student is thinking that where it is speeding up the most is where it has the greatest speed, rather than at the bottom of the ramp where it will be moving fastest. This leads them to make incorrect claims about the energy being the highest at C. (I)
This response suggests that the student is primarily thinking about energy as kinetic energy, and might even be thinking about it in terms of power ("speed up"), but does not yet account for potential energy. (C)
They’re thinking about gravity and how it affects the speed of the object, but their ideas need refinement. (V)
Which of the following options would best support Student A in being able to correctly respond to this question?
I would begin to build towards the conservation of energy by first having students debate which has more kinetic energy: a fast car, or a slower car that is accelerating. I expect that arguments for the slower car would touch on ideas of potential energy. This would then help us think about the energy of motion and the potential energy (that might result in motion). (C)
I’d organize a lab where students roll carts down a track and use a motion detector to determine when the cart is moving the fastest. We could then discuss how that relates to the conservation of energy. (I)
I would have students work in teams to build rollercoasters using balls and flexible tubing. They then would do a write up that includes identifying where the ball has the most potential energy, where it has a mixture of potential and kinetic, and where it has the most potential energy. (I)
Which answer best describes what student B's response indicates about their physics understanding?
While they have some idea about the forces on the cart and how it will accelerate they do not use this correctly to examine how the work done on the cart changes its energy. (I)
This student has some strong intuitive ideas about how an object can gain energy over time from a force, they don't seem to be considering the potential energy of the system that provided this force. (C)
They’re on the right track with gravity and motion — they just need help putting it all together. (V)
Which of the following options would best support Student B in being able to correctly respond to this question?
I would ask them to consider whether or not they think of the force of gravity as being associated with energy in this scenario. If they have not yet learned about potential energy, then I would start there by linking gravitational forces to gravitational potential energy. (C)
I’d organize a lab where students drop a ball from different heights and measure its speed with a motion sensor. We could then calculate the total kinetic energy using 1/2 mv^2 and use this information to develop a claim - evidence - reasoning statement about energy in this scenario. (I)
I would ask students to find a partner who had a different answer and discuss their ideas. (V)