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4 years ago

Why were epicycles necessary in ptolemy’s model of the universe?

2 answers:

N76 [4]4 years ago

4 0

Because Mars, Jupiter, and Saturn each appear to slow down, stop, move backwards for a while, then again slow down, stop, and start moving forward again. Each plant does this at some time during each year.

If they were simply moving in circles around the Earth, they couldn't do any of this. They would need to be moving on small circles attached to the big circles. The small ones are the 'epicycles'.

Liono4ka [1.6K]4 years ago

3 0

epicycles were orbits within orbits used to explain discrepancies between expected and observed planetary movement, including the appearance of planets slowing down, speeding up, and moving backward.

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You see lightning before you hear thunder because A) light waves can travel through a vacuum. B) sound waves cannot travel throu

Alex Ar [27]

C) light waves travel faster than sound waves

You were correct

3 0

4 years ago

Read 2 more answers

A meter stick is supported by a pivot at its center of mass. Assume that the meter stick is uniform and that the center of mass

iragen [17]

Answer:

64.5 cm

Explanation:

30 * 80 + x * 110 = 50* 190 => x = 64.5

5 0

3 years ago

As a diligent physics student, you carry out physics experiments at every opportunity. At this opportunity, you carry a 1.33 m l

deff fn [24]

Answer: 62 μT

Explanation:

Given

Length of rod, l = 1.33 m

Velocity of rod, v = 3.19 m/s

Induced emf, e = 0.263*10^-3 V

Using Faraday's law, the induced emf of a rod can be gotten by the formula

e = blv where,

e = induced emf of the rod

b = magnetic field of the rod

l = length of the rod

v = velocity of the rod. On substituting, we have

0.263*10^-3 = b * 1.33 * 3.19

0.263*10^-3 = b * 4.2427

b = 0.263*10^-3 / 4.2427

b = 0.0000620 T

b = 62 μT

Thus, the strength of the magnetic field is 62 μT

8 0

3 years ago

Read 2 more answers

Four forces are exerted on a disk of radius R that is free to spin about its center, as shown above. The magnitudes are proporti

Dmitry_Shevchenko [17]

The given magnitude of forces of F₁ = F₄, F₂ = F₃, F₁ = 2·F₂, give the

forces that exert zero net torque on the disk as the options;

(B) F₂

(D) F₄

<h3>How can the net torque on the disk be calculated?</h3>

The given parameters are;

F₁ = F₄

F₂ = F₃

F₁ = 2·F₂

Therefore;

F₄ = 2·F₂

In vector form, we have;

$\vec{F_4} = \mathbf{\frac{\sqrt{3} }{2} \cdot F_4 \cdot \hat i - 0.5 \cdot F_4 \hat j}$

$\vec{F_2} = \mathbf{ -F_2 \, \hat j}$

Clockwise moment due to F₄, M₁ = $-0.5 \times F_4 \, \hat j \times \dfrac{R}{2}$

Therefore;

$M_1 =- 0.5 \times 2 \times F_2 \, \hat j \times \dfrac{R}{2} = \mathbf{ -F_2 \, \hat j \times \dfrac{R}{2}}$

Counterclockwise moment due to F₂ = $-F_2 \, \hat j \times \dfrac{R}{2}$

Given that the clockwise moment due to F₄ = The counterclockwise moment due to F₂, we have;

Two forces that combine to exert zero net torque on the disk are;

F₂, and F₄

Which are the options; (B) F₂, and (D) F₄

Learn more about the resolution of vectors here:

brainly.com/question/1858958

4 0

2 years ago

Are the small sized gears only force, speed and distance, only speed

sesenic [268]

If the gears are of different sizes, they can be used to increase the power of a turning force. The smaller wheel turns more quickly but with less force, while the bigger one turns more slowly with more force. Cars and bicycles use gears to achieve amazing speeds our bodies could never match without help.

3 0

3 years ago