9514 1404 393
Answer:
68.6 m/s
Step-by-step explanation:
The speed at a given time is the derivative of the height at that time.
dh/dt = -9.8t
At t=7, the speed is ...
-9.8(7) = -68.6 . . . . . meters per second (downward)
The speed is 68.6 meters per second.
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<em>Additional comment</em>
Height is considered to be positive in the up direction, so velocity and acceleration are also positive in the up direction. The derivative of height will be the velocity. Its negative sign in this case indicates the object is moving in the downward direction. The speed is the magnitude (absolute value) of the velocity.
Given:
To find:
The quadrant in which 
lie.
Solution:
Quadrant concept:
In Quadrant I, all trigonometric ratios are positive.
In Quadrant II, only 
and 
are positive.
In Quadrant III, only 
and 
are positive.
In Quadrant IV, only 
and 
are positive.
We have,
Here, is negative and is also negative. It is possible, if 
lies in the Quadrant IV.
Therefore, the correct option is D.
They were supposed to flip 16/6 so that it's 6/16. Then multiply 5/3 by 6/16 to get 30/48, which becomes 5/8.
