Hey,
Today I took a 30 minute in-class exam, and got answers wrong strictly because i was not interpreting the question correctly. Its clear how these questions SHOULD be interpreted, but i'm trying to understand how I should be reading these problems.
(Previously we were given the formula's for kinetic motion, per section 1 of the EK book. This corresponds to section 1 of the TBR book.)
Using the above equations and adjusting the net for the effects of air resistance, Zacchini should place the center of the net at a displacment:
a. exactly equal to X
b. exactly equal to Xo
c. greater than x.
d. less than x.
My answer: a.
Credited answer: d.
Credited answering reasoning: Air resistance shortens flight path.
My answer reasoning: It says that we've already taken air resistance into account (via adjusting). Thus I expect his calculations to have adjusted for it, meaning X.
What do you think the question implied? Why do you think it implied that? Thanks!
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All of the following will affect the time of flight for a projectile experiencing no air resistance except:
I. the mass of the projectile.
II. the initial horizontal velocity of the projectile.
III. the initial vertical velocity of the projectile.
I said that ONLY I had 0 affect on the flight in the absence of air resistance.
The credited answer said that I and II had 0 affect on the flight in the absence of air resistance.
.... Isn't that only true for a 100% completely uniform flat surface? This would require that the entire plane was flat. The object firing the projectile is not on top of a hill, nor on the bottom of a hill. In the distant DISTANT horizon, there are no hills or valley's, what so ever. Additionally, the surface that this object is fired on is not a sphere-like object, else the curvature of the earth would make II valid. This seems like an extremely unreasonable assumption to me.
Thoughts?
Today I took a 30 minute in-class exam, and got answers wrong strictly because i was not interpreting the question correctly. Its clear how these questions SHOULD be interpreted, but i'm trying to understand how I should be reading these problems.
(Previously we were given the formula's for kinetic motion, per section 1 of the EK book. This corresponds to section 1 of the TBR book.)
Using the above equations and adjusting the net for the effects of air resistance, Zacchini should place the center of the net at a displacment:
a. exactly equal to X
b. exactly equal to Xo
c. greater than x.
d. less than x.
My answer: a.
Credited answer: d.
Credited answering reasoning: Air resistance shortens flight path.
My answer reasoning: It says that we've already taken air resistance into account (via adjusting). Thus I expect his calculations to have adjusted for it, meaning X.
What do you think the question implied? Why do you think it implied that? Thanks!
------------------------------------
All of the following will affect the time of flight for a projectile experiencing no air resistance except:
I. the mass of the projectile.
II. the initial horizontal velocity of the projectile.
III. the initial vertical velocity of the projectile.
I said that ONLY I had 0 affect on the flight in the absence of air resistance.
The credited answer said that I and II had 0 affect on the flight in the absence of air resistance.
.... Isn't that only true for a 100% completely uniform flat surface? This would require that the entire plane was flat. The object firing the projectile is not on top of a hill, nor on the bottom of a hill. In the distant DISTANT horizon, there are no hills or valley's, what so ever. Additionally, the surface that this object is fired on is not a sphere-like object, else the curvature of the earth would make II valid. This seems like an extremely unreasonable assumption to me.
Thoughts?
