Please try to help me with this TBR question!

[Bammy]

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I'm am feeling very confused! Please help! Any insight would be appreciated.

In the Physics Section I of the Berkeley Review on Passage #1
This question:

In the passage it says that a rock was kicked off the tip of a rocket on earth HORIZONTALLY. The answer is D and I understand that it is D because the Range formula doesn't have mass in it. Distance=rate x time

BUT then on Passage #5 (V)
This question:

In the passage a football is being kicked over a horizontal bar (to make a field goal).
In this question the answer is B and they are saying that the mass of a football DOES affect it's range.

So why in the first question I posted, does it say that the mass of the rock wouldn't affect the range but then in the second question I posted (from a different passage though) it says that the mass WOULD affect the footballs range? I'm confused!!

 

[makingthejump]

I'm confused too, your logic makes sense and I'm thinking exactly along the same lines. Seems like a book error or something

 

[justadream]

@Bammy
@makingthejump

I could be wrong but I think the difference is that in the first, the initial velocity is the same.

In the latter, the initial velocities are not the same (the heavier things will have smaller initial velocity). This is because if you kick with the same amount of energy, heavier things (e.g., a bowling ball) will not accelerate as much.

 

[Cawolf]

@justadream nailed it

 

[justadream]

@Cawolf

If "the mass of the football does not affect its range" is NOT TRUE, then the logic is that "mass DOES affect the range".

 

[makingthejump]

@Bammy
@makingthejump

I could be wrong but I think the difference is that in the first, the initial velocity is the same.

In the latter, the initial velocities are not the same (the heavier things will have smaller initial velocity). This is because if you kick with the same amount of energy, heavier things (e.g., a bowling ball) will not accelerate as much.

I think you are right! Things that are harder to stop are harder to start and vice versa.

 

[Bammy]

@Bammy
@makingthejump

I could be wrong but I think the difference is that in the first, the initial velocity is the same.

In the latter, the initial velocities are not the same (the heavier things will have smaller initial velocity). This is because if you kick with the same amount of energy, heavier things (e.g., a bowling ball) will not accelerate as much.

Thank you so much for the help!! But in the latter passage, it doesn't say anywhere that the football didn't have the same initial velocities? Or do we assume that the initial velocities are not the same because they didn't mention it in the passage?

Thanks again!! 🙂

 

[techfan]

Well in the football example we are assuming that the kicker can only kick with a certain force and that the lighter ball will go further since it has less inertia. The force is the same on the two balls so the initial acceleration is different (F=ma and m gets bigger and F stays the same so a has to go down), for the Galileo experiment we are told that the initial velocity is the same, so a stays constant and he is throwing the 2 kg with more force.

 

[Bammy]

Well in the football example we are assuming that the kicker can only kick with a certain force and that the lighter ball will go further since it has less inertia. The force is the same on the two balls so the initial acceleration is different (F=ma and m gets bigger and F stays the same so a has to go down), for the Galileo experiment we are told that the initial velocity is the same, so a stays constant and he is throwing the 2 kg with more force.

Thank you!!!

 

[texan2414]

@Cawolf

If "the mass of the football does not affect its range" is NOT TRUE, then the logic is that "mass DOES affect the range".

Are we doing VR section now haha 🙂