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3 years ago

Which of these assumptions is Ptolemy's model of planetary motion based on?

2 answers:

4 0

Ptolemy's model of planetary motion based on the fact that The sun moves around the earth.
Ptolemy thought that all celestial objects — including the planets, Sun, Moon, and stars — orbited Earth. Earth, in the center of the universe, did not move at all.

djverab [1.8K]3 years ago

3 0

Ptolemy's model of planetary motion is based on that the sun moves around the earth.

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A force acts on a 9.90 kg mobile object that moves from an initial position of to a final position of in 5.40 s. Find (a) the wo

horrorfan [7]

Given that,

Mass of object = 9.90 kg

Time =5.40 s

Suppose the force is (2.00i + 9.00j + 5.30k) N, initial position is (2.70i - 2.90j + 5.50k) m and final position is (-4.10i + 3.30j + 5.40k) m.

We need to calculate the displacement

Using formula of displacement

$s=r_{2}-r_{1}$

Where, $r_{1}$ = initial position

$r_{2}$ = final position

Put the value into the formula

$s= (-4.10i + 3.30j + 5.40k)-(2.70i - 2.90j + 5.50k)$

$s= -6.80i+6.20j-0.1k$

(a). We need to calculate the work done on the object

Using formula of work done

$W=F\cdot s$

Put the value into the formula

$W=(2.00i + 9.00j + 5.30k)\cdot (-6.80i+6.20j-0.1k)$

$W=-13.6+55.8-0.53$

$W=41.67\ J$

(b). We need to calculate the average power due to the force during that interval

Using formula of power

$P=\dfrac{W}{t}$

Where, P = power

W = work

t = time

Put the value into the formula

$P=\dfrac{41.67}{5.40}$

$P=7.71\ Watt$

(c). We need to calculate the angle between vectors

Using formula of angle

$\theta=\cos^{-1}(\dfrac{r_{1}r_{2}}{|r_{1}||r_{2}|})$

Put the value into the formula

$\theta=\cos^{-1}\dfrac{(-4.10i + 3.30j + 5.40k)\cdot(2.70i - 2.90j + 5.50k)}{7.54\times6.778})$

$\theta=79.7^{\circ}$

Hence, (a). The work done on the object by the force in the 5.40 s interval is 41.67 J.

(b). The average power due to the force during that interval is 7.71 Watt.

(c). The angle between vectors is 79.7°

7 0

4 years ago

You are operating a pwc in an area where swimmers are in the water. When must you slow your pwc to "slow, no wake speed"?.

Lostsunrise [7]

You should slow your pwc to "slow, no wake speed" when within 100 feet of anchored vessels or non-motorized craft.

This is the process of operating a personal watercraft at the slowest possible speed.

This helps to maintain steerage which prevents different forms of accident or risks when in motion in the water.

Read more about Slow-no-wake here brainly.com/question/10410716

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2 years ago

Magnitude of the normal force exerted by en in the figure below. What is the

vekshin1

Answer:

Explanation:

Reason is that the suitcase is exerted downward and when it moves downward the equation is mgsin tita

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3 years ago

A tortoise and a hare are having a 1,000-meter race. The tortolse runs the

lukranit [14]

Answer:2 hours

Explanation:

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Let x define the position of an object such that x =

timama [110]

See the attached picture for answers

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2 years ago