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3 years ago

How much physical activity should an adult have each week?

Physics

2 answers:

il63 [147K]3 years ago

5 0

Answer:

D. 30 minutes per day, 5 days a week

Explanation:

As per World Health Organization (WHO) physical activity includes the following :

- Leisure time physical activity like running

- Occupational work

- Household chores

- Sports

An adult (aged 18-64) should do at least 150 minutes of physical activity per week. That can be divided over 5 days a week as well with 30 minutes of physical activity per day.

Mars2501 [29]3 years ago

4 0

d 30 minutes a day , 5 days a week

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An x-ray beam of wavelength 1.4×10−10m makes an angle of 20° with a set of planes in a crystal(the Bragg angle)causing first ord

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Answer:

Second order line appears at 43.33° Bragg angle.

Explanation:

When there is a scattering of x- rays from the crystal lattice and interference occurs, this is known as Bragg's law.

The Bragg's diffraction equation is :

$n\lambda=2d\sin\theta$ .....(1)

Here n is order of constructive interference, λ is wavelength of x-ray beam, d is the inter spacing distance of lattice and θ is the Bragg's angle or scattering angle.

Given :

Wavelength, λ = 1.4 x 10⁻¹⁰ m

Bragg's angle, θ = 20°

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Substitute these value in equation (1).

$1\times1.4\times10^{-10} =2d\sin20$

d = 2.04 x 10⁻¹⁰ m

For second order constructive interference, let the Bragg's angle be θ₁.

Substitute 2 for n, 2.04 x 10⁻¹⁰ m for d and 1.4 x 10⁻¹⁰ m for λ in equation (1).

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3 years ago

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Answer:

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Explanation:

Given:

Intensity $I = 8.8$ $\frac{W}{m^{2} }$

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From the formula of radiation pressure in terms of intensity,

$P = \frac{I}{c}$

Where $P =$ radiation pressure, $c =$ speed of light

We know value of speed of light,

$c = 3 \times 10^{8}$ $\frac{m}{s}$

Put all values in above equation,

$P = \frac{8.8}{3 \times 10^{8} }$

$P = 2.933 \times 10^{-8}$ Pa

Therefore, the value of radiation pressure is $2.933 \times 10^{-8}$ Pa

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3 years ago

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Kobotan [32]

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3 years ago