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storchak [24]
3 years ago
8

Using a dish-shaped mirror, a solar cooker concentrates the sun's energy onto a pot for cooking. A cooker with a 1.2-m-diameter

dish focuses the sun's energy onto a pot with a diameter of 25 cm What is the intensity at the base of the pot
Physics
1 answer:
Alekssandra [29.7K]3 years ago
3 0

Answer:

26500 W/m²

Explanation:

Given that:

The diameter of the dish d = 1.2 m

Assuming the Solar power P capture by the dish = 1300 W

The surface area of the pot is calculated by using the formula:

= \pi r^2

\pi \dfrac{d^2}{4}

where; the diameter = 25 cm

Area = \pi \dfrac{d^2}{4}

Area = \pi \dfrac{0.25^2}{4}

Area = 0.049 m²

The intensity is calculated by using the formula

I = power/area

I = 1300/0.049

I = 26530.6 W/m²

I ≅ 26500 W/m²

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We are asked to calculate the gain in kinetic energy of earth.

The kinetic energy of meteorite is calculated as -

                                       Kinetic\ energy\ [K.E]\ =\frac{1}{2} mv^2

                                                             =\frac{1}{2}50kg*[1000\ m/s]^2

                                                               =\frac{1}{2}50* 10^{6}\ J

                                                               =25*10^6\ J    

Here, J stands for Joule which is the S.I unit of energy.

Hence,\ the\ kinetic\ energy\ gained\ by\ earth\ is\ 25*10^6\ J

4 0
3 years ago
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To make a given sound seem twice as loud, how should a musician change the intensity of the sound?
Serhud [2]

Answer:

C. Quadruple the intensity

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I ∝ A²

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When the given sound is twice loud as the initial value, then the new amplitude is twice the former.

A₂ = 2A₁

I_2 = \frac{I_1A_2^2}{A_1^2} \\\\I_2 = \frac{I_1(2A_1)^2}{A_1^2} \\\\I_2 = \frac{4I_1A_1^2}{A_1^2}\\\\ I_2 = 4I_1

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3 0
3 years ago
The length of a certain wire is kept same while its radius is doubled. what is the new resistivity of this wire?
anastassius [24]
The text does not specify whether the resistance R of the wire must be kept the same or not: here I assume R must be kept the same.

The relationship between the resistance and the resistivity of a wire is
\rho =  \frac{AR}{L}
where
\rho is the resistivity
A is the cross-sectional area
R is the resistance
L is the wire length

the cross-sectional area is given by
A=\pi r^2
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For the new wire, the length L is kept the same (L'=L) while the radius is doubled (r'=2r), so the new resistivity is
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4 0
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