Romeo ( mass = 70 kg ) feels a gravitational attraction for Juliet ( mass = 50 kg ). If hey are 20 m apart, find the force.

Championship swimmers take about 22 s and about 30 arm strokes to move through the water in a 50 m freestyle race.The swimmer's

Tasya [4]

Answer:

4400 Joules

73.33 Joules

25.9325 Joules

Explanation:

P = Power = 800 W

t = Time = 22 s

F = Force

r = Radius of arm = 90 cm

Energy

$E=P\times t\\\Rightarrow E=800\times 22\\\Rightarrow E=17600\ J$

As the efficiency is 25%

$E=0.25\times 17600\\\Rightarrow E=4400\ J$

Energy used in the race is 4400 Joules

Half of the energy is used in the arm

$E=\frac{4400}{2}=2200\ J$

So, per stroke of paddle

$E=\frac{2200}{30}=73.33\ J$

The energy expenditure per arm stroke is 73.33 Joules

Displacement will be the half of the perimeter of the circle

$s=\frac{1}{2}\times 2\pi r\\\Rightarrow s=\frac{1}{2}\times 2\pi 0.9\\\Rightarrow s=2.82743$

Work done

$W=F\times s\\\Rightarrow F=\frac{W}{s}\\\Rightarrow F=\frac{73.33}{2.82743}\\\Rightarrow W=25.9352\ J$

The average force of the hand on the water is 25.9325 Joules

3 0

3 years ago

A U-shaped tube open to the air at both ends contains some mercury. A quantity of water is carefully poured into the left arm of

Gekata [30.6K]

Answer:

a) $P=2450\ Pa$

b) $\delta h=23.162\ cm$

Explanation:

Given:

height of water in one arm of the u-tube, $h_w=25\ cm=0.25\ m$

a)

Gauge pressure at the water-mercury interface,:

$P=\rho_w.g.h_w$

we've the density of the water $=1000\ kg.m^{-3}$

$P=1000\times 9.8\times 0.25$

$P=2450\ Pa$

b)

Now the same pressure is balanced by the mercury column in the other arm of the tube:

$\rho_w.g.h_w=\rho_m.g.h_m$

$1000\times 9.8\times 0.25=13600\times 9.8\times h_m$

$h_m=0.01838\ m=1.838\ cm$

<u>Now the difference in the column is :</u>

$\delta h=h_w-h_m$

$\delta h=25-1.838$

$\delta h=23.162\ cm$

7 0

3 years ago

A suitable model for air could be b-b's moving rapidly around and colliding with each other.

solong [7]

The answer to your qestion is true

5 0

3 years ago

Read 2 more answers

A LETTER FROM THE LORAX

KengaRu [80]

Answer:

Explanation:

You could try to say how helpful they are what they are and what they do

5 0

3 years ago

Read 2 more answers

Find the orbital speed of an ice cube in the rings of Saturn. The mass of Saturn is 5.68 x 1026 kg, and use an orbital radius of

Studentka2010 [4]

The orbital speed of an ice cube in the rings of saturn is approximately 3.56 * 10^6 m/s

<h3>What is law of gravitation?</h3>

The law of gravitation states that the force of gravitation is directly proportional to the product of the masses and inversely proportional to the distance between the masses. Mathematically;

F = GMm/r²

where

M and m are the mass of ice cube and

Recall that;

s = Gm1/r^2

Also;

F = sm²

Substitute to have;

s = m²/F

For the centripetal acceleration

a = v²/r

Such that;

v²/r = Gm/r²

v² = Gm/r

v = √Gm/r

Substitute the given parameters into the formula to have:

V = √6.67×10^-11 * 5.68 x 10^26 / 3.00 x 10^5

V = 355358.97m/s = 3.56 * 10^6 m/s

Therefore the orbital speed of an ice cube in the rings of saturn is approximately 3.56 * 10^6 m/s

Learn more on orbital speed here: brainly.com/question/7260440

#SPJ1

3 0

1 year ago