Air Resistance Question

[Lunasly]

Q: Air resistance would decease all of the following EXCEPT:

A) Range
B) Height
C) Velocity
D) Time

Can someone please explain why velocity wouldn't decrease and the other 3 would?

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[hellocubed]

What exactly is the question stem?

Because I can tell you for a FACT that the answer is "time" if it is a question about firing a projectile into the air in a parabolic shape and timing how long it takes o hit the ground.



Velocity should be one of the first attributes decreased.

 

[Lunasly]

That is the entire question from EK. Honestly, when I read this I thought that air resistance would effect all of them.

EK says that it effects all of them except velocity (they describe this answer choice as initial velocity in the back of the book).

My entire idea of how this works is that if you shoot a projectile, then the velocity will decrease (immediatly) because the acceleration due to gravity will be counteracted by air resistance. This in turn effects the maximum height of the projectile and the time it will reach the ground. I thought it would also effect range because, well, air resistance, to my knowledge, works in all planes (x,y,z).

 

[hellocubed]

We had a topic on this a few days ago, sorry I cannot find it.

1.) Time may NOT be affected (notice the may).
When you fire a projectile up, it reaches the apex sooner. But then it takes longer to reach the ground due to decreased terminal velocity.
Hence the time you gain on the trip up cancels the time you gain on the trip down. (according to BR)

2.) Height, of course is affected

3.) Reach, of course is also affected

Velocity should be affected always. I actually cannot think of a single example where it wouldn't.


It has to be a flaw, the answer is Velocity.

 

[Lunasly]

Yeah I read that time MAY be effected in EK as well. Perhaps it is a flaw.

Thanks.