A tennis ball machine serves a ball vertically into the air from a height of 2 feet, with an initial speed of 120 feet per secon
d. After how many seconds does the ball attain it's maximum height?
1 answer:
Answer:
The maximum height is reached after 3.75 seconds.
Step-by-step explanation:
Assuming the deceleration due to gravity is unaided by air resistance, gravity causes the ball to lose vertical speed at the rate of 32 ft/s every second. The initial vertical speed of 120 ft/s will decline to zero when t satisfies ...
... 120 ft/s - (32 ft/s²)t = 0
... (120 ft/s)/(32 ft/s²) = t = 3.75 s
The ball will not go any higher after its vertical speed is zero.
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9514 1404 393
Answer:
A. √13
Step-by-step explanation:
You can make an educated guess and come to the right conclusion.
The triangle is nearly an equilateral triangle. A triangle with two sides 3 and an angle of 60° would have a third side of 3. A triangle with two sides of 4 and an angle of 60° would have a third side of 4.
So, the third side must be between 3 and 4. Here is an evaluation of the answer choices:
__
A -- between 3 and 4, the correct choice
B -- 3, too short
C -- 1.73, too short
D -- more than 4, too long
__
The question can be answered using your triangle solver app on your calculator, or using the Law of Cosines.
c = √(a^2 +b^2 -2ab·cos(C))
c = √(3^2 +4^2 -2·3·4·(1/2)) = √(9 +16 -12)
c = √13 . . . . . length of the side opposite the 60° angle
