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Dennis_Churaev [7]
3 years ago
14

A 144-g baseball is dropped from a tree 11.0m above the ground.A.With what speed would it hit the ground if air resistance could

be ignored?Express your answer to three significant figures and include the appropriate units.B.If it actually hits the ground with a speed of 7.50m/s , what is the magnitude of the average force of air resistance exerted on it?Express your answer to three significant figures and include the appropriate units.
Physics
1 answer:
nikitadnepr [17]3 years ago
5 0

Answer:

a. 14.68m/s

b. 1.043N

Explanation:

a.

Given

Mass = m = 144g = 0.144kg

Height = h = 11m

Using energy conservation,

½mv² = mgh where g = 9.8m/s² ----- divide both sides by m

½v² = gh ---- divide both sides by ½

v² = 2gh

v = √2gh

v = √(2 * 9.8 * 11)

v = 14.68332387438212m/s

v = 14.68m/s ----- Approximated

b.

v = 7.5m/s

By definition, “the average force of air resistance,”

When work done against air resistance is solved by multiplying height by the average force of resistance ------ by definition

i.e. W = -Fh

Minus is used because F and h points to different direction (when viewed as vectors).

This is proved by:

W = Fhcos(180) because h points toward the direction of motion (downward) while F points opposite.

W = Fh * -1

W = Fh

Using energy conservation,

mgh - Fh = ½mv² ---- Make Fh, the subject of formula

Fh = mgh - ½mv² ---- Divide through by h

F = mg - mv²/2h

F = 0.144 * 9.8 - 0.144 * 7.5²/(2 * 11)

F = 1.043N

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A force acts on a body of mass 13 kg initially at rest. The force
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4 0
3 years ago
HELP I NEED THIS ANSWERED AS FAST AS POSSIBLE!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
WITCHER [35]

Displacement is d  


Vf² = Vi² + 2 g d  


(-20²) = (+10²) + 2 (-9.8) d  


-19.6 d = 300  


d = -15.3 m  


negative means lower


time is t  


d = Vi t + 1/2 g t²



-15.3 = 10 t + (-4.9) t²



4.9 t² - 10 t -15.3 = 0  


t = 3.06 s

Hope this helps -John

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4 years ago
Is the temperature and density of Earth's crust high or low? Why?
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Explanation:

7 0
4 years ago
PLEASE HELP ASAP
Dmitrij [34]
The answer should be B
3 0
3 years ago
Read 2 more answers
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