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3 years ago

I need help with this

Physics

1 answer:

laila [671]3 years ago

7 0

Answer:

D, B, A, E, C

Explanation:

KE = m*g*h

PE = (1/2)m*v²

1. d

2. b

3. a

4. e

5. c

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6) Find the speed a spherical raindrop would attain by falling from 4.00 km. Do this:a) In the absence of air dragb) In the pres

sleet_krkn [62]

We are asked to determine the velocity of a rain drop if it falls from 4 km.

To do that we will use the following formula:

$2ah=v_f^2-v_0^2$

Where:

$\begin{gathered} a=\text{ acceleration} \\ h=\text{ height} \\ v_f,v_0=\text{ final and initial velocity} \end{gathered}$

If we assume the initial velocity to be 0 we get:

$2ah=v_f^2$

The acceleration is the acceleration due to gravity:

$2gh=v_f^2$

Now, we take the square root to both sides:

$\sqrt{2gh}=v_f$

Now, we substitute the values:

$\sqrt{2(9.8\frac{m}{s^2})(4000m)}=v_f$

solving the operations:

$280\frac{m}{s}=v$

Therefore, the velocity without air drag is 280 m/s.

Part B. we are asked to determine the velocity if there is air drag. To do that we will use the following formula:

$F_d=\frac{1}{2}C\rho_{air}Av^2$

Where:

$\begin{gathered} F_d=drag\text{ force} \\ C=\text{ constant} \\ \rho_{air}=\text{ density of air} \\ A=\text{ area} \\ v=\text{ velocity} \end{gathered}$

We need to determine the drag force. To do that we will use the following free-body diagram:

Since the velocity that the raindrop reaches is the terminal velocity and its a constant velocity this means that the acceleration is zero and therefore the forces are balanced:

$F_d=mg$

Now, we determine the mass of the raindrop using the following formula:

$m=\rho_{water}V$

Where:

$\begin{gathered} \rho_{water}=\text{ density of water} \\ V=\text{ volume} \end{gathered}$

The volume is the volume of a sphere, therefore:

$m=\rho_{water}(\frac{4}{3}\pi r^3)$

Since the diameter of the raindrop is 3 millimeters, the radius is 1.5 mm or 0.0015 meters. Substituting we get:

$m=(0.98\times10^3\frac{kg}{m^3})(\frac{4}{3}\pi(0.0015m)^3)$

Solving the operations:

$m=1.39\times10^{-5}kg$

Now, we substitute the values in the formula for the drag force:

$F_d=(1.39\times10^{-5}kg)(9.8\frac{m}{s^2})$

Solving the operations:

$F_d=1.36\times10^{-4}N$

Now, we substitute in the formula:

$1.36\times10^{-4}N=\frac{1}{2}C\rho_{air}Av^2$

Now, we solve for the velocity:

$\frac{1.36\times10^{-4}N}{\frac{1}{2}C\rho_{air}A}=v^2$

Now, we substitute the values. We will use the area of a circle:

$\frac{1.36\times10^{-4}N}{\frac{1}{2}(0.45)(1.21\frac{kg}{m^3})(\pi r^2)}=v^2$

Substituting the radius:

$\frac{1.36\cdot10^{-4}N}{\frac{1}{2}(0.45)(1.21\frac{kg}{m^{3}})(\pi(0.0015m)^2)}=v^2$

Solving the operations:

$70.67\frac{m^2}{s^2}=v^2$

Now, we take the square root to both sides:

$\begin{gathered} \sqrt{70.67\frac{m^2}{s^2}}=v \\ \\ 8.4\frac{m}{s}=v \\ \end{gathered}$

Therefore, the velocity is 8.4 m/s

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1 year ago

Question 8: Cosmology (8 points)

STatiana [176]

Big bang happened about 13.7 billion years ago in our universe.

<h3>Describe the beginning of the universe according to the big bang theory?</h3>

According to the big bang theory, about 13.7 billion years ago, an explosive expansion began, expanding our universe outwards faster than the speed of light.

<h3>Describe the future of the universe according to the flat model?</h3>

According to the flat model, the universe is infinite and will continue to expand forever because the universe is expanding.

<h3>What is cosmic background radiation? </h3>

Cosmic background radiation is a weak radio-frequency radiation that is traveling through outer space in every direction. It is the residual radiation of the big bang, when the universe was very hot.

<h3>How do observations of the cosmic background radiation provide evidence to support the big bang theory? </h3>

The Big Bang theory predicts that the early universe was a very hot place and that as it expands, the gas within it cools. Thus the universe has all over radiation which is called the “cosmic microwave background".

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2 years ago

calculate the force required to take away a flat corcular plate of radius 0.01m from the surface of water. the surface tention o

leonid [27]

Answer:

$Force = 0.0047175\ N$

Explanation:

Given

$T = 0.075N/m$ --- Surface Tension

$r = 0.01m$ --- Radius

Required

Determine the required force

First, we calculate the circumference (C) of the circular plate

$C= 2\pi r$

$C= 2 * \frac{22}{7} * 0.01m$

$C= \frac{2 * 22 * 0.01}{7}m$

$C= \frac{0.44}{7}m$

$C= 0.0629 m$

The applied force is then calculated using;

$Force = C * T$

$Force = 0.0629m * 0.075N/m$

$Force = 0.0047175\ N$

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3 years ago

How is aperture measured? What do the measurements mean?

gulaghasi [49]

Aperture is measured in F-stops, in which the f-stops is the amount of light allowed to pass through the aperture, which simply put means that the smaller the aperture, the higher the f-stops. What it does is reduce the amount of light that reaches the film, so the higher the f-stops, the less light reaches the film.

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The magnetic field is the region of space where a charged object experiences magnetic force when it is moving.

When a charged particle such as an electron or proton moves inside a conductor, magnetic lines of force rotate around the particle. This relative motion causes the magnetic field to generate.

Thus, If the charged particle moves in the magnetic field or electric field, then it experiences magnetic force or electric force because of its magnetic or electric properties.

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2 years ago