DASI-P - Apples

What important physics idea is this question targeting?

That gravity is independent of mass. (I)
A key difference between gravitational force and gravitational potential energy. (C)
How to apply Newton's Laws in real-world settings. (V)

Student A's response:
"2 has the most gravitational force because of how high it is and because of how big it is. Something that high must have a lot of force put into it to get it there and it will hit the ground the hardest because of that force."

Which answer best describes what student A's response indicates about their physics understanding?

The mention of how hard it hits the ground shows a solid grasp of acceleration — they just didn’t explain it in terms of gravitational force. (I)
This response reflects a common early student idea where motion, energy, and force are treated somewhat interchangeably. (C)
They’re thinking about gravity and how it affects objects of different height and mass, but their ideas need refinement. (V)

Which of the following options would best support Student B in being able to correctly respond to this question?

I’d have Student A work with a partner who gave a different answer — ideally one who focused on mass alone — and ask them to compare reasoning. Then I’d give both students a scale and ask them to “test” their predictions by weighing the apples or estimating mass. This would open up a conversation about what’s measurable and what “force” means in context. (C)
I’d organize a lab where students drop apples (or balls) from different heights and measure the impact force with a force sensor — then use that data to test Student A's claim that gravitational force increases with height. (I)
I’d design an activity where students share and debate their different ideas about gravity. That way, they can hear each other’s thinking and come to a better understanding. (V)

Student B's response:
“They all experience the same gravitational force. My reasoning for this statement is because all objects feel the same gravitational force which is 9.8 m/s. The distance and possibly the air resistance are the only things that could change the outcome but I don’t think they matter here.”

Which answer best describes what student B's response indicates about their physics understanding?

They clearly understand that gravitational force is the same for all objects, but need support in understanding the units and direction of the gravitational force. (I)
This indicates that they understand that there is something uniform in how objects respond to gravitational forces, but haven’t yet distinguished between force and acceleration. (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’d hand out four cards to sort with the following statements: “Gravitational force is always 9.8 kg-m/s2,” “Gravitational acceleration is always 9.8m/s2,” “All objects fall at the same rate,” and "All objects feel the same effects of gravity." I’d have the class sort and defend which are true, false, or confusing. This would help tease apart the misunderstanding the student has. (C)
I’d organize a lab where students drop apples (or balls) of different masses from different heights and measure the time it takes for them to fall— then use that data to test Student B's claim that gravitational force is the same. (I)
I would ask the class to read the relevant section in our book on g = 9.8 m/s2 and then discuss with a partner. (V)