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vodomira [7]
3 years ago
9

Studies of gymnasts show that their high rate of injuries to the Achilles tendon is due to tensions in the tendon that typically

reach 12 times body weight. That force is provided by a pair of muscles, each exerting a force at 23 ∘ to the vertical, with their horizontal components opposite.
For a 53-kg gymnast, find the force in each of these muscles.
Express your answers using two significant figures separated by a comma.
Physics
1 answer:
konstantin123 [22]3 years ago
5 0
The horizontal components, being opposite in direction, will produce a shearing effect on the tendon, leading to injury. Thus, they will be added.
As the angle of 23 is from the vertical, we calculate the horizontal component by using
Weight acting * sin(23)
And multiply it by 2 to get the total shearing force
The weight acting is 12 times their body weight. Thus:
53 * 9.81 * 12 = 6239.2 Newtons
The total force acting on the tendon:
2 * sin(23) * 6239.2
= 4,880
= 4,900 Newtons (2 significant figures)
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<h2>Answer:</h2>

Torque = <em>2.05 x 10²⁸ Nm</em>

Energy = <em>3.54 x 10³³ J</em>

Average power = <em>1.02 x 10²⁸ W</em>

<h2>Explanation:</h2>

(a) Torque (τ) is the rotational effect of a given force.  

It is given by

τ = I x α          -------------(i)

Where;

I = rotational inertia of the object

α = angular acceleration of the object.

In this case, the object is the Earth. Therefore,

I = 9.71 x 10³⁷ kg m²

α = ω / t

Where;

ω = angular velocity of earth = 2π rad / day

<em>Since </em>

<em>1 day = 24 hours and 1 hour = 3600seconds</em>

<em>1 day = 24 x 3600 seconds = 86400seconds</em>

<em>=> ω = 2π rad / 86400seconds</em>

<em>=> ω = 7.29 × 10⁻⁵ rad/s</em>

<em />

t = 4 days = 4 x 24 x 3600 seconds = 345600 seconds

=> α = ω / t

=> α = 7.29 × 10⁻⁵ / 345600

=> α = (7.29 × 10⁻⁵) / (3.456 x 10⁵)

=> α = (7.29 × 10⁻⁵⁻⁵) / (3.456)

=> α = (7.29 × 10⁻¹⁰) / (3.456)

=> α = 2.11 × 10⁻¹⁰ rad/s²

Now substitute the values of I and α into equation (i)

τ = 9.71 x 10³⁷ x 2.11 × 10⁻¹⁰

τ = 9.71 x 10²⁷ x 2.11

τ = 20.5 x 10²⁷ Nm

τ = 2.05 x 10²⁸ Nm

(ii) The energy (rotational energy) E is given by;

E = \frac{1}{2} x I x ω

E = \frac{1}{2} x 9.71 x 10³⁷ x 7.29 × 10⁻⁵

E = 35.4 x 10³² J

E = 3.54 x 10³³ J

(iii) The average power P, is given by;

P = E / t

P = 3.54 x 10³³ / 345600

P = 1.02 x 10²⁸ W

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Answer:

Explanation:

First, let's review the ideal gas law, PV = nRT. In this equation, 'P' is the pressure in atmospheres, 'V' is the volume in liters, 'n' is the number of particles in moles, 'T' is the temperature in Kelvin and 'R' is the ideal gas constant (0.0821 liter atmospheres per moles Kelvin).

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29.4855 grams of chlorophyll

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MW of diethyl ether (C2H5OC2H5) = 74 g/mol

Number of moles of solvent = mass/MW = 187.4/74 = 2.532 mol

Let the moles of solute (chlorophyll) be y

Total moles of solution = moles of solute + moles of solvent = (y + 2.532) mol

Mole fraction of solvent = moles of solvent/total moles of solution

0.987 = 2.532/(y + 2.532)

y + 2.532 = 2.532/0.987

y + 2.532 = 2.565

y = 2.565 - 2.532 = 0.033

Moles of solute (chlorophyll) = 0.033 mol

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The article is not found here but surveys are important because they are representative samples of a population.

<h3>What is a survey?</h3>

A survey is a useful tool based on population samples, which is used to make statistical analyses in a given investigation.

Differences in surveys are generally due to small sample sizes, which may lead to errors in the analysis of data.

In conclusion, the article is not found here but surveys are important because they are representative samples of a population.

Learn more about surveys here:

brainly.com/question/13624055

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