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Nadya [2.5K]
3 years ago
12

The apparent westward movement of a planet against the background of stars is called

Physics
1 answer:
Lubov Fominskaja [6]3 years ago
6 0

Answer:

Retrogade Motion

Explanation:

The planet movement is called a retrogade motion meaning that it is moving in an opposite path to the stars.

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You have two golf balls that differ only in their surfaces. one has dimples, while the other is smooth. if you were to drop the
il63 [147K]

Answer: the golf ball with smooth surface would hit the ground first.


Jusitification:


An analysis of forces show two vertical forces acting on the golf balls.


1) one force is the weight (mg) which is vertical downward


2) the other force is the drag force exerted by the air on the golf balls, and it is vertical upward.


3) the drag force opposes the weight, so the acceleration downward is determined by the difference of the weiight and the drag force, until the balls reach the terminal speed (when the drag force equals the weight).


4) the drag force depends on the shape and area of the object falling. Being the surface of one ball smooth implies that the drag force will be less than the one on the other ball.


5) less drag force implies that the terminal velocity of the smooth ball will he higher, ant then it will hit the ground first.

3 0
3 years ago
Need help!! How much energy is used by a microwave if 15 A of current run through it for a period of 20 minutes?
svetoff [14.1K]

Well first of all, here's something you're going to need:

          Power = (energy) / (time)          1 watt = (1 joule) per second          
          Energy = (power) x (time)          1 joule = (1 watt) x (1 second)

At this point, your progress grinds to a stop, because, technically, the
current alone doesn't tell you the power.  In other words, 'Amperes'
alone doesn't give you the 'watts'.

             Power (watts) = (amperes) times (volts) .

So you need to either go ask somebody or else <em>assume</em> the <u>voltage</u>
of the outlet that the microwave oven is plugged into.  Without it,
the question can't be answered.

I'm going to assume that you live and go to school somewhere in the USA,
Canada, or Mexico.  If that's true, then the outlets in your house supply
electrical energy at 120 volts, and everything you plug into them is designed
to run on 120 volts.  Now you have enough information to solve the problem.

         Power = (15 amperes) x (120 volts) = 1,800 watts

         Energy = (power) x (time) =

                         (1,800 watts) x (20 minutes) x (60 seconds/minute) =

                           2,160,000 watt-seconds = <em>2,160,000 joules</em>

3 0
3 years ago
X-rays with wavelengths of 0.95 nm are detected at a scattering angle of straight theta in a Compton-scattering experiment, as s
SIZIF [17.4K]

Answer:

The scattering angle is 0.80

Explanation:

As we know  

Wave length = h/mc (1-cos α) --1

W = mc^2

m = E/c^2

Substituting this in equation 1 we get  

Wavelength = hc/E (1-cos α)

Substituting the given values, we get -  

0.95*10^-9 = [(6.626 *10^-34 * 2.998 *10^8)/5.111*1000*1.6*10^-19} (1-cos α)

(1-cos α) = 1.14 *10^-10

cos α = 1- 1.14 *10^-10

α = 0.80

3 0
3 years ago
Three stars, each with the mass of our sun, form an equilateral triangle with sides 1.0×1012m long. (This triangle would just ab
tatiyna

Answer:

period of rotation is 9.9843 years

Explanation:

Given data

sides  = 1.0×10^12 m

to find out

period of rotation

solution

first we use the gravititional formula i.e

F(g) = 2 F cos 30

here F = G  × mass(sun)² / radius²

F = 6.67 × 10^{-11} × (1.99× 10^{30})² / (1× 10^{30})²

so

F(g) = 2  ×  6.67 × 10^{-11} × (1.99× 10^{30})² / (1× 10^{30})²  ×  (1.73/2)

F(g) = 4.57 ×  10^{26} N

and

by the law of sines

r/sin30 = s/sin120

so r will be

r = 1.0×10^12  (0.5/.87)

r = 5.75 ×  10^{11} m

we know that gravititional force = centripetal force

so  here

centripetal force = mv² /r

centripetal force = 1.99× 10^{30} v² / 5.75 ×  10^{11}

so

4.57 ×  10^{26}  = mv² /r

4.57 ×  10^{26}  = 1.99× 10^{30} v² / 5.75 ×  10^{11}

v² = 4.57 ×  10^{26} × 5.75 ×  10^{11} / 1.99× [tex]10^{30}

and

v = 11480 m/sec

and we know period of rotation formula

t = d /v

t = 2 \pi r /v

t = 2 × \pi ×  5.75 ×  [tex]10^{11} / 11480

t = 314 × [tex]10^{5} / 31536000 year

t = 9.9843 year

so period of rotation is 9.9843 years

6 0
3 years ago
When the skater starts 7 above the ground, how does the speed of the skater at the bottom of the track compare to the speed of t
bixtya [17]

Answer:

A. twice as fast.

Explanation:

m = Mass of skater

h = Height from where the skater starts

g = Acceleration due to gravity = 9.81 m/s²

Here the kinetic and potential energies balance each other

K=P\\\Rightarrow \frac{1}{2}mv^2=mgh\\\Rightarrow v=\sqrt{2gh}

Velocity from 7 m

v_1=\sqrt{2g7}

Velocity from 4 m

v_2=\sqrt{2g4}

Dividing the two equations

\frac{v_1}{v_2}=\frac{\sqrt{2g7}}{\sqrt{2g4}}\\\Rightarrow \frac{v_1}{v_2}=1.32\approx 2\\\Rightarrow v_1\approx 2v_2

So, the velocity of the skater is twice as fast

8 0
3 years ago
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