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2 years ago

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Why does the sun appear to move across the sky over the course of the day? A. because the sun revolves around Earth B. because E

arth revolves around the sun C. because the sun rotates on its axis D. because Earth rotates on its axis. PLease answer quickly next question is 50 points

2 answers:

aev [14]2 years ago

6 0

Pretty sure it's:
D. Earth rotates on its axis

bagirrra123 [75]2 years ago

3 0

Answer:

i would say B

Explanation:

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Choose the best description of a magnetic field line

LiRa [457]

Answer:

A magnetic field line can never cross another field line. The magnetic field is unique at every point in space. Magnetic field lines are continuous and unbroken, forming closed loops. Magnetic field lines are defined to begin on the north pole of a magnet and terminate on the south pole.

Explanation:

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3 years ago

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A 30 kg mass and a 20 kg mass are joined by a light rigid rod and this system is free to rotate in the plane of the page about a

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55 J

Explanation:

Kinetic energy is given as: 0.5MV^2 where M is the mass and V is the speed of rotation. Since the masses are point masses, we calculate the point mass for each mass.

M1 = 30*0.2^2 = 1.2kgm^2

M2 = 20*0.4^2 = 3.2kgm^2

V = 5 rad/s

Calculating using the formula above, we obtain :

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3 years ago

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The inductive reactance of the circuit is exactly twice the resistance: XL=2R. Adjust the phasor that represents the voltage acr

SVETLANKA909090 [29]

Answer:

∅= $63.43^{0}$

Explanation:

z=impedance

$x_{l}$ =2R

R=R

The resultant of the resistances in the circuit is called impedance

$x_{l}$ is inductive reactance of the circuit

R is the resistance of the resistor

z= $\sqrt{xl^{2}+R^2 }$

z= $\sqrt{2R^{2}+R^2 }$

Z= $\sqrt{5R^2}$

Z=R $\sqrt{5}$ ohms

tan∅=2R/R

tan∅=2

∅=Tan^-1(2)

∅= $63.43^{0}$

phase angle is ∅= $63.43^{0}$

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2 years ago

The air inside a balloon exerts a force of 1.5 n on an area of 0.5 m^2. what is the pressure inside the balloon?

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Pressure=force/area
1.5/0.5=3Pa

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3 years ago

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Barack is playing basketball in his back yard. He takes a shot 7.0 m from the basket (measured along the ground), shooting at an

VMariaS [17]

Answer:

The time of flight of the ball is 1.06 seconds.

Explanation:

Given $\Delta x=7\ m$

$\theta=45 \°$

Also, $\Delta y=(3.5-2)=1.5\ m$

$a_x=0\ and\ a_y=-9.81\ m/s^2$

Let us say the velocity in the x-direction is $v_x$ and in the y-direction is $v_y$ . And acceleration in the x-direction is $a_x$ and in the y-direction is $a_y$ .

Also, $\Delta x\ and\ \Delta y$ is distance covered in x and y direction respectively. And $t$ is the time taken by the ball to hit the backboard.

We can write $v_x=v_0cos(45)\ and\ v_y=v_0sin(45)$ . Where $v_0$ is velocity of ball.

Now,

$\Delta x=v_x\times t+\frac{1}{2}\times a_x\times t^2\\ \Delta x=v_x\times t+\frac{1}{2}\times 0\times t^2\\\Delta x=v_xt$

$\Delta x=v_0cos(45)\times t\\7=v_0cos(45)\times t\\\\t=\frac{7}{v_0cos(45)}$

Also,

$\Delta y=v_y\times t+\frac{1}{2}\times a_y\times t^2\\ 1.5=v_0sin(45)\times \frac{7}{v_0cos(45)}+\frac{1}{2}\times (-9.81)\times(\frac{7}{v_0cos(45)} )^2\\\\1.5=7-\frac{481}{(v_0)^2}\\ \\\frac{481}{(v_0)^2}=5.5\\\\(v_0)^2=\frac{481}{5.5}\\ \\(v_0)^2=87.45\\\\v_0=\sqrt{87.45}=9.35\ m/s$ .

Plugging this value in

$t=\frac{7}{v_0cos(45)}\\ \\t=\frac{7}{9.35\times 0.707}\\ \\t=\frac{7}{6.611}$

$t=1.06\ seconds$

So, the time of flight of the ball is 1.06 seconds.

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3 years ago