PS question on AAMC 5

[phatty925]

IN THE PHYSICAL SCIENCES SECTION:

#104) why can the answer not be B? is it because in that case, the oxidation state of Cd would change from +2 to +1?

#130) the solutions manual uses the equation x=1/2at^2 to figure out the time the snowball is in the air. however, since we're trying to figure out how long the snowball is in the air during its horizontal flight, how come the manual uses 20 meters (the vertical height of point A) for the value of x?

thanks!

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[Mudd]

Exactly correct on 104. There is nothing in solution to reduce Cd from +2 to +1, so it remains a dication.

On #130, the range of the object is found by multiplying the horizontal velocity by the flight time. The flight time depends on the y-component, which has a height of 20m, which leads to a t = 2s. They simply found range by using the given horizontal velocity of 25 m/s and the time of 2s.

 

[phatty925]

so does the flight time always depend on the vertical displacement (height)?

 

[Mudd]

When there is a uniform force acting on the object is in the y direction, then yes. In the case of projectile motion and free fall, that's the case.