Confused about Free Falling Bodies in Vacuum: Acceleration or Velocity?

AI Thread Summary
In a vacuum, both a pingpong ball and a golf ball experience the same acceleration due to gravity, regardless of their mass. The confusion arises from the distinction between acceleration and velocity; while both objects have the same acceleration, their velocities differ as they fall. The answer key incorrectly states that they have the same velocity halfway through their fall, which contradicts fundamental physics principles. The discussion highlights the importance of understanding the difference between these concepts, particularly in the context of standardized testing. Ultimately, both objects share the same acceleration, but their velocities are not equal at all points during the fall.
Max Leo
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Here is an unsettling question from a practice set that I've been working on today. Unsettling because the answer key contradicts my answer so I need a second thought.

A pingpong ball and a golf ball are dropped in a vacuum chamber from the same height and at the same time. When they have fallen halfway, they have the same

A. Potential energy
B. Kinetic energy
C. Acceleration
D. Velocity

My answer is C. Acceleration since this is what I've learned from college physics. But the answer key says it is D. Velocity. So I'm quite confused.

Help me guys. Thank you in advance! :)
 
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Max Leo said:
Here is an unsettling question from a practice set that I've been working on today. Unsettling because the answer key contradicts my answer so I need a second thought.

A pingpong ball and a golf ball are dropped in a vacuum chamber from the same height and at the same time. When they have fallen halfway, they have the same

A. Potential energy
B. Kinetic energy
C. Acceleration
D. Velocity

My answer is C. Acceleration since this is what I've learned from college physics. But the answer key says it is D. Velocity. So I'm quite confused.

Help me guys. Thank you in advance! :)
I think there are two answers of this question.
 
Both the accelerations and the velocities are the same.

ehild
 
Do not believe something just because you are told it - is there a good reason from the laws of physics to believe that C is correct?
What are your reasons from physics for rejecting each one of the other answers?
As you go through the reasons, the correct answer should occur to you.
 
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Likes Satvik Pandey
Thanks guys! They have the same acceleration so the change in magnitude of velocity must be the same at any given time. It's just this is a question from an admission test and I find it unsettling that the machine will mark one correct and the other wrong...
 
Yes, that is a common flaw in machine mediated tests.
 

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