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madam [21]
3 years ago
14

A woman walked 115 m. As she did so, her speed increased from 4.20 m/s to 5.00 m/s. How long did it take her to walk this distan

ce?
Physics
1 answer:
ASHA 777 [7]3 years ago
5 0

Answer:

25 seconds

Explanation:

Assuming the woman is accelerating at a constant rate of a \;\;m/s^2 from the initial velocity, u=4.20 m/s, to the final velocity, v=5.00 m/s.

Let she takes t seconds to cover the distance, s=115 m.

As acceleration, a=\frac{v-u}{t}=\frac{5-4.2}{t}

\Rightarrow at=0.8\cdots(i)

Now, from the equation of motion

s=ut+\frac 12 at^2

\Rightarrow s=ut+\frac 12 at(t)

\Rightarrow 115=4.2t+\frac 12 \times 0.8 t [ from equation (i)]

\Rightarrow 115=(4.2+0.4)t

\Rightarrow t= 115/4.6 = 25 seconds.

Hence, she takes 25 seconds to walk the distance.

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now by Newton's II law we know that

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Answer:

La velocidad media es 5 \frac{km}{h}, que equivale a 1.389 \frac{m}{s}

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La velocidad media relaciona el cambio de la posición con el tiempo empleado en efectuar dicho cambio. Por lo que se calcula como la distancia recorrida por un objeto dividido por el tiempo transcurrido:

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En este caso:

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Entonces, reemplazando en la definición de velocidad media:

velocidad=\frac{10 km}{2 h}= \frac{10,000 m}{7,200 s}

Resolviendo se obtiene:

velocidad=5 \frac{km}{h}= 1.389\frac{m}{s}

<u><em>La velocidad media es 5 </em></u>\frac{km}{h}<u><em>, que equivale a 1.389 </em></u>\frac{m}{s}<u><em></em></u>

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Answer:

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speed of wave V = 20.0 × 0.2

speed of wave V = 4 m/s

Therefore, the speed of the wave 4 m/s

6 0
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