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3 years ago

Brainliest and 100 POINTS

Physics

2 answers:

anastassius [24]3 years ago

8 0

Reflection- serious thought or consideration

Absorption- the process or action by which one thing absorbs or is absorbed by another.

Diffusion- the spreading of something more widely.

Diffraction- the process by which a beam of light or other system of waves is spread out as a result of passing through a narrow aperture or across an edge, typically accompanied by interference between the wave forms produced.

Refraction- measurement of the focusing characteristics of an eye or eyes

Natasha_Volkova [10]3 years ago

6 0

Reflection is where the sound seems to bounce off the instrument and play back at its surroundings

Absorption is the opposite of reflection, where a physical object absorbs the sound rather than bounces it away.

Diffusion is an even spread of a sound across a given area

Diffraction is the bending of sound waves around barriers

Refraction is the bending of sound propagation trajectories

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A river 800m wide flows at the rate of 5km/h . A swimmer who can swim at 10km/h in still water wants to cross the river straight

LuckyWell [14K]

Answer:

At an angle of $30^{\circ}$

Explanation:

Assume the river flows from East to West so for the swimmer to cross across it, assume he crosses it from West to East.

The resultant speed will be given by

$R= \sqrt {10^{2}-5^{2}=\sqrt {75}\approx 8.66 km/h\\Direction=sin^{-1}\frac {5}{10}\approx 30^{\circ}$

6 0

2 years ago

I need help doing this i don’t understand what to do

Hatshy [7]

Answer:

You need to write an essay with 800 to 1,200 words. That talks about the significance of one of the seminal works (Definition- a work that strongly influenced people. Example: Martin Luther King Jr's speech "I Have A Dream") in the unit and how it connects to current issues (Example- Politics). It should be clearly stated and should be well supported by research (Example- a trustworthy article talking about its influence). You should properly cite at least 3 good sources from different perspectives. (Example- a republicans view for one source, a democratic for another, and a neutral for the third) You should also use direct quotes (Example: "Let them eat cake." - Marie Antoinette) and paraphrase- put it in your own words. (Example: Marie Antoinette said that they should eat cake.) I hope this helps, good luck! :)

Explanation:

7 0

2 years ago

A 72-kg boy is surfing and catches a wave which gives him an initial speed of 1.6 m/s. He then drops through a height of 1.61 m,

chubhunter [2.5K]

Answer:

2849.98 J

Explanation:

From the question,

Work done by the boy = change Potential energy of the boy + change in kinetic energy of the boy

W = ΔP + ΔK..................... Equation 1

Where W = work done by the boy, ΔP = change in potential energy of the boy, ΔK = Change in kinetic energy of the boy.

But,

ΔP = mgΔh.................... Equation 2

ΔK = 1/2mΔv²................. Equation 3

Where m = mass of the boy, Δh = change in height of the boy, Δv = change in velocity of the boy.

Substitute equation 2 and 3 into equation 1

W = mgΔh+1/2mΔv²................. Equation 4

Given: m = 72 kg, Δh = 1.61 m, Δv = 8.5-1.6 = 6.9 m/s, g = 9.8 m/s²

Substitute into equation 4

W = 72(9.8)(1.61)+1/2(72)(6.9²)

W = 1136.016+1713.96

W = 2849.98 J

8 0

3 years ago

If the net force on an object is in a negative direction, what will the direction of the resulting acceleration be?

Verdich [7]

Newton's 2nd law says: Force = (mass) x (acceleration) .

I wrote Force and acceleration in bold letters because
they're both vectors ... they have size and direction.

The equation is saying that the Force and the acceleration
are both in the same direction.

5 0

3 years ago

A ball thrown horizontally at vi = 30.0 m/s travels a horizontal distance of d = 55.0 m before hitting the ground. from what hei

tekilochka [14]

Assume no air resistance, and g = 9.8 m/s².

Let
x = angle that the initial velocity makes with the horizontal.
u = 30 cos(x), horizontal velocity
v = 30 sin(x), vertical launch velocity

The horizontal distance traveled is 55 m, therefore the time of flight is
t = 55/[30 cos(x)] = 1.8333 sec(x) s

With regard to the vertical velocity, and the time of flight,obtain
[30 sin(x)]*(1.8333 sec(x)) + (1/2)*(-9.8)*(1.8333 sec(x))² = 0
55 tan(x) - 16.469 sec²x = 0
55 tan(x) - 16.469[1 + tan²x] = 0
16.469 tan²x - 55 tan(x) + 16.469 = 0
tan²x - 3.3396 tan(x) + 1 = 0

Solve with the quadratic formula.
tan(x) = 0.5[3.3396 +/- √(7.153)] = 3.007 or 0.3326
Therefore
x = 71.6° or x = 18.4°

The time of flight is
t = 1.8333 sec(x) = 5.8096 s or 1.932 s
The initial vertical velocity is
v = 30 sin(x) = 28.467 m/s or 9.468 m/s
The horizontal velocity is
u = 30 cos(x) = 9.467 m/s or 28.469 m/s

If t = 5.8096 s,
u*t = 9.467*5.8096 = 55 m (Correct)
or
u*t = 28.469*15.8096 = 165.4 m (Incorrect)

Therefore, reject x = 18.4°. The correct solution is
t = 5.8096 s
x = 71.6°
u = 9.467 m/s
v = 28.467 m/s

The height from which the ball was thrown is
h = 28.467*5.8096 - 0.5*9.8*5.8096² = -110.4 m
The ball was thrown from a height of 110.4 m

Answer: h = 110.4 m

7 0

2 years ago