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nekit [7.7K]
3 years ago
14

A sphere of uniform density with mass 21 kg and radius 0.8 m is spinning, making one complete revolution every 0.8 s. the center

of mass of the sphere has a speed of 8 m/s. (a) what is the rotational kinetic energy of the sphere?
Physics
1 answer:
kompoz [17]3 years ago
8 0
Using the equation;
TE = 1/2mv^2(1+2); where k = 2/5 for a solid sphere; V is the velocity, and m is the mass.
Total energy = 0.5 × 21 × 8² (7/5)
                    = 940.8 J
The rotational kinetic energy of the sphere is 940.8 J

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Consider the third period of the periodic table. Which element has the smallest atomic radius?
Anettt [7]
According to periodic trends in the periodic table, the atomic radius decreases from left to right. 

In period three, the element with the smallest atomic radius would be the element in the rightmost area. Protons increase as it goes to the right, which would mean they pull in electrons closer which decreases the size. 

So in period 3, the element with the smallest atomic radius is Argon (Ar). 
3 0
3 years ago
What are some examples of gravitational forces that keep an object in orbit? Pls give at least 2-3 example if you can.​
Lelu [443]

Answer:

Without any external forces a moving object will continue to move in a straight line. The gravitational force between the two objects will provide the centripetal force to keep the objects moving around one another.

1. satellite in orbit around the earth             (motion of earth is negligible)

2. moon in orbit around the earth     (center of motion several thousand miles        

                                                             from center of earth)

3. earth in orbit around sun    (center of rotation close to center of sun)

4. binary stars         (if masses of stars are equal center of rotation is in middle)

3 0
3 years ago
What are the coordinates of the point that is 1/5 of the way from A(-7,-4) to B(3, 6)?
Olegator [25]

Answer:

coordinate will be

r = (1.33,4.33)

Explanation:

As we know that if a point will divide two given coordinates in m : n ratio

then in that case the point is given as

x = \frac{mx_1 + nx_2}{m+n}

y = \frac{my_1 + ny_2}{m+n}

here we know that two points are

(-7, -4) and (3, 6)

and the ratio is given as 1 : 5

now from above formula we will have

x = \frac{1(-7) + 5(3)}{1 + 5} = 1.33

y = \frac{1(-4) + 5(6)}{1 + 5} = 4.33

so coordinate will be

r = (1.33, 4.33)

7 0
3 years ago
Which statements are true for two oppositely charged, isolated parallel plates: C=capacitance, U=stored energy (Q and -Q = charg
vlada-n [284]

Answer:

Explanation:

1) True. The stored energy (U) is proportional to the electric field strength (E). The electric field strength decreases when a dielectric is introduced hence inserting a dielectric decreases U.

2) False. From the formula C=\frac{Q}{V}=\frac{Q}{Vd}, capacitance is inversely proportional to distance hence if the distance is doubled, capacitance decreases.

3) False. As the distance between the electric field and the object increases, its electric field decreases.

4) False. If a dielectric is inserted, the plates are further separated. Q stays the same.

5) True. The electric field strength decreases when a dielectric is introduced and  capacitance is inversely proportional to electric field hence Inserting a dielectric increases C

6) True. If a dielectric is inserted, the plates are further separated. Q stays the same.

7) True. When the distance is doubled, U increases

7 0
3 years ago
At an air show a jet flies directly toward the stands at a speed of 1200 km/h, emitting a frequency of 3500 Hz, on a day when th
kenny6666 [7]

Answer:

(a): The frequency received by the observers is f'= 138,062.28 Hz.

(b): When the plane flies directly away from them, they receive a frequency of f'= 1772.46 Hz.

Explanation:

Vf= 333.33 m/s

Vo= 0 m/s

V= 342 m/s

f= 3500 Hz

(a) f' = f * ( V / (V - Vf) )

f'= 138062.28 Hz

(b) f'= f* ( V / (V - (- Vf) )

f'= 1772.46 Hz

4 0
3 years ago
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