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2 years ago

A house has a roof (colored gray) with the dimensions shown in the drawing. Determine the magnitude of the net force that the

Physics

1 answer:

Sav [38]2 years ago

5 0

The magnitude of the net force that the atmosphere applies to the roof when the outside pressure drops suddenly is 1.9 x 10⁵ N.

<h3>What is pressure?</h3>

The pressure is the amount of force applied per unit area.

Pressure p = Force/Area

Given is a house has a roof (colored gray) with the dimensions shown in the drawing. The outside pressure drops suddenly by 13.2 mm of mercury, before the pressure in the attic can adjust.

The pressure difference ΔP = 13.2 mm of Hg

The length of the roof l = 14.5m

the breadth of the roof h = 4.21m

The force exerted by pressure is

Force, F = P x A

= (13.2 mm of Hg) [(133 N/m²) /1 mm of Hg ](14.5 x 4.21)

= 107,170.6 N

Then the net vertical force

Fnet = 2F cos30

Fnet = 2 ( 107,170.6) cos30

Fnet = 185625 N

Fnet =1.9 x 10⁵ N

The direction of the force is downwards, since the horizontal components of the forces cancel each other.

Hence, magnitude of the net force is 1.9 x 10⁵ N

Learn more about pressure.

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A certain 100W light bulb has an efficiency of 95%. How much thermal energy will this light bulb add to the inside of a room in

Usimov [2.4K]

Since the bulb consumes 100 watts of power and its efficiency is 95%,
it generates 95 watts of light energy and 5 watts of heat energy whenever
it's turned on.

5 watts means 5 joules of energy per second.

(2.5 hours) x (3,600 seconds/hour) = 9,000 seconds

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3 years ago

if the instantaneous current in the circuit is giveen by I=3 sin theta amperes, the rms value of the current will be

Kisachek [45]

Answer:

$I_{rms}=2.12\ A$

Explanation:

Given that,

The instantaneous current in the circuit is giveen by :

$I=3\sin\theta\ A$

We need to find the rms value of the current.

The general equation of current is given by :

$I=I_o\sin\theta$

It means, $I_o=3\ A$

We know that,

$I_{rms}=\dfrac{I_o}{\sqrt2}\\\\=\dfrac{3}{\sqrt2}\\\\=2.12\ A$

So, the rms value of current is 2.12 A.

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3 years ago

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NikAS [45]

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3 years ago

A cord is used to vertically lower an initially stationary block of mass M = 3.6 kg at a constant downward acceleration of g/7.

dalvyx [7]

Answer:

(a) $W_c=127.008 J$

(b) $W_g=148.176 J$

(c) K.E. = 21.168 J

(d) $v=3.4293m.s^{-1}$

Explanation:

Given:

mass of a block, M = 3.6 kg

initial velocity of the block, $u=0 m.s^{-1}$

constant downward acceleration, $a_d= \frac{g}{7}$

$\Rightarrow$ That a constant upward acceleration of $\frac{6g}{7}$ is applied in the presence of gravity.

∴ $a=- \frac{6g}{7}$

height through which the block falls, d = 4.2 m

(a)

Force by the cord on the block,

$F_c= M\times a$

$F_c=3.6\times (-6)\times\frac{9.8}{7}$

$F_c=-30.24 N$

∴Work by the cord on the block,

$W_c= F_c\times d$

$W_c= -30.24\times 4.2$

We take -ve sign because the direction of force and the displacement are opposite to each other.

$W_c=-127.008 J$

(b)

Force on the block due to gravity:

$F_g= M.g$

∵the gravity is naturally a constant and we cannot change it

$F_g=3.6\times 9.8$

$F_g=35.28 N$

∴Work by the gravity on the block,

$W_g=F_g\times d$

$W_g=35.28\times 4.2$

$W_g=148.176 J$

(c)

Kinetic energy of the block will be equal to the net work done i.e. sum of the two works.

mathematically:

$K.E.= W_g+W_c$

$K.E.=148.176-127.008$

K.E. = 21.168 J

(d)

From the equation of motion:

$v^2=u^2+2a_d\times d$

putting the respective values:

$v=\sqrt{0^2+2\times \frac{9.8}{7}\times 4.2 }$

$v=3.4293m.s^{-1}$ is the speed when the block has fallen 4.2 meters.

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3 years ago

Which energy transfer occurs when a cube of ice is placed in a glass of<br> water?

Daniel [21]

Acetic acid is a weak acid and sodium hydroxide is strong base. Salts of the two will hydrolyse to give basic solution. So, at neutral point, pH of the solution will be greater than 8.

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3 years ago