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statuscvo [17]
3 years ago
9

Which is true

Physics
2 answers:
velikii [3]3 years ago
8 0

Answer:

D no salt like all matter is composed of molecules

Explanation: something like salt is a compound it is made of more than one element, but it is not a molecule because the bond that holds NaCl together is an ionic bond.

Leokris [45]3 years ago
7 0
The answer is most likely b
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lutik1710 [3]

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2. Earth layers compare in egg layer it is hard on the outside

Explanation:

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If the speedometer of your car reads a constant speedometer of your car reads a constant speed of 40km/hr , can you say the car
Harrizon [31]
I think u can say thats a constant velocity, but remember if ur turning, or going around a curve, that is also changing velocity. Hope this helps have a great day! 
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Dark matter may explain _____.
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Dark matter may explain <span>unexpected orbital velocities of stars in galaxies.</span>
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Una cuerda de 20 pies se estira entre dos arboles. Un peso W cuelga del centro de la cuerda hace que el punto medio de la misma
Galina-37 [17]

Answer:

La magnitud de la masa del peso es 78.447 libras-masa.

Explanation:

La tensión es una fuerza de reacción de la cuerda causada por la acción de una fuerza externa. En este caso, esa fuerza externa es el peso que cuelga en el centro de la cuerda. Abajo hemos adjuntado una representación simplificada del enunciado.

Por las leyes de Newton, tenemos la siguiente ecuación de equilibrio conformada por tres fuerzas:

\vec T_{1} + \vec T_{2} + \vec W = (0, 0)\, [N] (1)

Donde:

\vec T_{1}, \vec T_{2} - Tensiones a cada lado de la cuerda, en newtons.

\vec W- Peso, en newtons.

Si sabemos que \vec T_{1} = T\cdot (\cos \alpha, \sin \alpha), \vec T_{2} = T\cdot (-\cos \alpha, \sin \alpha) y \vec W = W\cdot (0, -1), entonces tenemos la siguiente ecuación vectorial:

T\cdot (\cos \alpha, \sin \alpha) + T\cdot (-\cos\alpha, \sin \alpha) + W\cdot (0, -1) = (0,0)

T\cdot (0, 2\cdot \sin \alpha) = W\cdot (0, 1)

Esto permite reducir la anterior expresión a una fórmula escalar:

2\cdot T\cdot \sin \alpha = W

Donde \alpha es el ángulo de inclinación de la cuerda, medido en grados sexagesimales.

El ángulo de inclinación de la cuerda se determina mediante la siguiente fórmula trigonométrica inversa es:

\alpha = \tan^{-1} \left(\frac{2\,ft}{10\,ft}\right)

\alpha \approx 11.310^{\circ}

Si conocemos que \alpha \approx 11.310^{\circ} y T = 200\,lbf, entonces la magnitud del peso es:

W = 2\cdot (200\,lb)\cdot \sin 11.310^{\circ}

W \approx 78.447\,lbf

En el Sistema Imperial, las fuerzas son medidas en forma gravitacional, entonces la magnitud de la fuerza gravitacional del peso equivale a la magnitud de su masa. En síntesis, la magnitud de la masa es 78.447\,lbm.

La magnitud de la masa del peso es 78.447 libras-masa.

7 0
3 years ago
Sonar is used to determine the speed of an object. A 38.0-kHz signal is sent out, and a 40.0-kHz signal is returned. If the spee
ANEK [815]

Answer:

The velocity is  v  =  8.743 \ m/s

Explanation:

From the question we are told that

    The frequency of the signal sent out  is  f_s  =  38.0 \ kHz  =  38.0 *10^{3} \ Hz

    The frequency of the signal received is  f_r  =  40.0 \ kHz  =  40.0 *10^{3} \ Hz

     The  speed of sound is  v_s  =  341 \ m/s

Generally the frequency of the sound received is  mathematically represented as

         f_r =  f_s  [\frac{v_s  + v}{v_s  - v} ]

where v is the velocity of the object

       =>      40 *10^{3} =  38 *10^{3} *   [\frac{341  + v}{341  - v} ]

       =>      1.05263 = \frac{341+v }{341-v}

       =>   358.94 - 1.05263v  =  341 + v

      =>    17.947 =  2.05263 v

      =>    v  =  8.743 \ m/s

7 0
3 years ago
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