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2 years ago

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The brick wall (of thermal conductivity 1.12 W/m · ◦ C) of a building has dimensions of 2.8 m by 5 m and is 8 cm thick. How much

heat flows through the wall in a 16.7 h period when the average inside and outside temperatures are, respectively, 12◦C and 3◦C? Answer in units of

1 answer:

hichkok12 [17]2 years ago

5 0

Answer:

Explanation:

If H be the heat flowing in time t through an area of A having thickness d

H = k A x ( θ₂ - θ₁ ) t / d , k is thermal conductivity , ( θ₂ - θ₁ ) is temperature difference of walls

putting the given values

= (1.12 x 2.8x 5 x 9 x 16.7 x 60 x 60) / .08

= 1.06 x 10⁸ J .

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You and your friend throw balloons filled with water from the roof of a several story apartment house. You simply drop a balloon

Aleks [24]

Answer:

Height = 53.361 m

Explanation:

There are two balloons being thrown down, one with initial speed (u1) = 0 and the other with initial speed (u2) = 43.12

From the given information we make the following summary

$u_{1}$ = 0m/s

$t_{1}$ = t

$u_{2}$ = 43.12m/s

$t_{2}$ = (t-2.2)s

The distance by the first balloon is

$D = u_{1} t_{1} + \frac{1}{2} at_{1}^2$

where

a = 9.8m/s2

Inputting the values

$D = (0)t + \frac{1}{2} (9.8)t^2\\ D = 4.9t^2$

The distance traveled by the second balloon

$D = u_{2} t_{2} + \frac{1}{2} at_{2}^2$

Inputting the values

$D = (43.12)(t-2.2) + \frac{1}{2} (9.8)(t-2.2)^2$

simplifying

$D = 4.9t^2 + 21.56t -71.148$

Substituting D of the first balloon into the D of the second balloon and solving

$4.9t^2 = 4.9t^2 + 21.56t -71.148 \\ 21.56t = 71.148\\ t = 3.3s$

Now we know the value of t. We input this into the equation of the first balloon the to get height of the apartment

$D = 4.9(3.3)^2\\ D = 53.361 m$

7 0

2 years ago

A neutral solid metal sphere of radius 0.1 m is at the origin, polarized by a point charge of 2 × 10−8 C at location m. At locat

liraira [26]

Answer: E = $1.8 *10 ^{4} N$

Explanation: The formulae for intensity of an electric field of a solid metal sphere relative to a point is given below

$E =\frac{Kq}{r^{2} }$ r

where $k=9* 10^{9}N/m^{2}$ , $q=2 *10 ^{-8} c$ , r = 0.1m r = is the position vector of the charge.

it has been stated in the question that the charge is placed at the center thus it has no position vector.

$E=\frac{9 * 10^{9}* 2* 10^{-8} }{0.1^{2} }\\ =\frac{18* 10^{1} }{0.01} \\=\frac{18* 10^{1} }{1 *10^{-2} } = 1.8*10^{4} N$

6 0

2 years ago

A trampoline spring has a force constant k = 800 N/m and is stretched exactly 17.5cm. What is the energy required to do this?

Artist 52 [7]

Answer:

the energy required for the extension is 12.25 J

Explanation:

Given;

force constant of trampoline spring, k = 800 N/m

extension of trampoline spring, x = 17.5 cm = 0.175 m

The energy required for the extension is calculated as;

E = ¹/₂kx²

E = 0.5 x 800 x 0.175²

E = 12.25 J

Therefore, the energy required for the extension is 12.25 J

6 0

2 years ago

Force F acts between two charges, q1 and q2, separated by a distance d. If q1 is increased to twice its original value and the d

vodka [1.7K]

Okay, haven't done physics in years, let's see if I remember this.

So Coulomb's Law states that $F = k \frac{Q_1Q_2}{d^2}$ so if we double the charge on $Q_1$ and double the distance to $(2d)$ we plug these into the equation to find

<span> $F_{new} = k \frac{2Q_1Q_2}{(2d)^2}=k \frac{2Q_1Q_2}{4d^2} = \frac{2}{4} \cdot k \frac{Q_1Q_2}{d^2} = \frac{1}{2} \cdot F_{old}$ </span>

So we see the new force is exactly 1/2 of the old force so your answer should be $\frac{1}{2}F$ if I can remember my physics correctly.

8 0

3 years ago

Read 2 more answers

Help asap plz !!! Use the circuit diagram to decide if the lightbulb will

nata0808 [166]

Answer:

I wish I knew the answer to that question

4 0

3 years ago