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Irina-Kira [14]

3 years ago

14

In which situation is work being done?

1 answer:

Keith_Richards [23]3 years ago

4 0

Answer: D. The force and displacement are in the same direction.

Explanation:

The Work $W$ done by a Force $F$ refers to the release of potential energy from a body that is moved by the application of that force to overcome a resistance along a path with distance $d$ .

Work is a scalar magnitude, and its unit in the International System of Units is the Joule (like energy).

Now, when the applied force is constant and the direction of the force and the direction of the displacement are <u>parallel</u>, the equation to calculate it is:

$W=(F)(d)$ (1)

When they are not parallel, both directions form an angle, let's call it $\alpha$ . In that case the expression to calculate the Work is:

$W=Fdcos{\alpha}$ (2)

When the force and displacement are perpendicular to each other, $\alpha=90\°$ and <u>no work is done</u>.

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During light activity, a 70-kg person may generate 200 kcal

Lerok [7]

Answer:

$2.75387\ ^{\circ}$

Explanation:

m = Mass of person = 70 kg

c = Specific heat of human body = $0.83\ J/kg^{\circ}C$

$\Delta T$ = Change in temperature

Time taken is 1 hour

Heat is given by

$Q=mc\Delta T\\\Rightarrow \Delta T=\dfrac{Q}{mc}\\\Rightarrow \Delta T=\dfrac{0.8\times 200\times 1}{70\times 0.83}\\\Rightarrow \Delta T=2.75387\ ^{\circ}C$

The rise in temperature is $2.75387\ ^{\circ}C$

3 0

3 years ago

Find a numerical value for rhoearth, the average density of the earth in kilograms per cubic meter. Use 6378km for the radius of

mylen [45]

Answer:

density = 5520 kg/m^3

Explanation:

given that

radius of earth = 6378 km

G = 6.67 x 10⁻¹¹ m³/kg.s²

g = 9.80 m/s²

we know,

$g = \dfrac{GM}{r^2}$

mass of earth

$M = \dfrac{gr^2}{G}$

$M = \dfrac{9.8 \times (6378 \times 10^3)^2}{6.67 \times 10^{-11}}$

M = 5.972 x 10²⁴ kg

density = $\dfrac{mass}{volume}$

V = volume of the earth = 4/3πr³

V = 4/3 x 3.14 x (6378 x 10³)³

V = 1.08 x 10²¹ m³

density = $\dfrac{5.972\times 10^{24}}{1.08\times 10^{21}}$

density = 5.52 x 10³ kg/m^3

density = 5520 kg/m^3

8 0

2 years ago

What does a cell use to eliminate a substance that is too large to leave by diffusion?

zysi [14]

<span>a cell eliminates endocytosis.

</span>

6 0

3 years ago

krek1111 [17]

Explanation:

the table and the wooden block

6 0

3 years ago

Read 2 more answers

A bicycle tire has a pressure of 7.00×105 N/m2 at a temperature of 18.0ºC and contains 2.00 L of gas. What will its pressure be

stepan [7]

Answer:

$p_2 = 664081 N/m^{2}$

Explanation:

from the ideal gas law we have

PV = mRT

$P = \rho RT$

$\rho = \frac{P}{RT}$

HERE R is gas constant for dry air = 287 J K^{-1} kg^{-1}

$\rho = \frac{7.00 10^{5}}{287(18+273)}$

$\rho = 8.38 kg/m^{3}$

We know by ideal gas law

$\rho = \frac{m_1}{V_1}$

$m_1 = \rho V_1 = 8.38 *2*10^{-3}$

$m_1 = 0.0167 kg$

for m_2

$m_2 = \rho V_i - V_removed$

$m_2 = 8.38*(.002 - 10^{-4})$

$m_2 = 0.0159 kg$

WE KNOW

PV = mRT

V, R and T are constant therefore we have

P is directly proportional to mass

$\frac{p_2}{p_1}=\frac{m_2}{m_1}$

$p_2 = p_1 * \frac{m_2}{m_1}$

$p_2 =7*10^{5} * \frac {.0159}{0.0167}$

$p_2 = 664081 N/m^{2}$

8 0

2 years ago