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3 years ago

The fall of a body on the earth's surface cannot be a complete free fall why ?

Physics

1 answer:

leonid [27]3 years ago

3 0

Explanation:

because the boy has larger surface area due to which he offers the larger air resistance which decreases the acceleration so, he will fall towards the earth's surface approximately with constant velocity.

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Which of the following is described here? "Point your skis straight down the fall line with your skis parallel and about a foot

elena55 [62]

answer d. down hill schussing

Explanation:

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3 years ago

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What traits did Sir William Gilbert have that made him a good scientist?

11111nata11111 [884]

Gave him good advice to others

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3 years ago

slab of ice floats on water with a large portion submerged beneath the water surface. The slab is in the shape of a rectangular

n200080 [17]

Answer:

a) $\%V = 87.36\,\%$ , b) $x = 1.248\,m$ , c) $F_{B} = 176488.341\,N$ , d) Six polar bears.

Explanation:

a) The slab of ice is modelled by the Archimedes' Principles and the Newton's Laws, whose equation of equilibrium is:

$\Sigma F =\rho_{w}\cdot g \cdot A \cdot x-\rho_{i}\cdot g\cdot V = 0$

The height of the ice submerged is:

$\rho_{w}\cdot A \cdot x = \rho_{i}\cdot V$

$x = \frac{\rho_{i}\cdot V}{\rho_{w}\cdot A}$

$x = \frac{\left(900\,\frac{kg}{m^{3}}\right)\cdot (20\,m^{3})}{\left(1030\,\frac{kg}{m^{3}} \right)\cdot (14\,m^{2})}$

$x = 1.248\,m$

The percentage of the volume of the ice that is submerged is:

$\%V = \frac{(1.248\,m)\cdot (14\,m^{2})}{20\,m^{3}} \times 100\,\%$

$\%V = 87.36\,\%$

b) The height of the portion of the ice that is submerged is:

$x = 1.248\,m$

c) The buoyant force acting on the ice is:

$F_{B} = \left(1030\,\frac{kg}{m^{3}} \right)\cdot (1.248\,m)\cdot (14\,m^{2})\cdot \left(9.807\,\frac{m}{s^{2}} \right)$

$F_{B} = 176488.341\,N$

d) The new system is modelled after the Archimedes' Principle and Newton's Laws:

$\Sigma F = -n\cdot m_{bear}\cdot g-\rho_{i}\cdot V \cdot g + \rho_{w}\cdot V\cdot g = 0$

The number of polar bear is cleared in the equation:

$n\cdot m_{bear} = (\rho_{w} - \rho_{i})\cdot V$

$n = \frac{(\rho_{w}-\rho_{i})\cdot V}{m_{bear}}$

$n = \frac{\left(1030\,\frac{kg}{m^{3}} - 900\,\frac{kg}{m^{3}} \right)\cdot (20\,m^{3})}{400\,kg}$

$n = 6.5$

The maximum number of polar bears that slab could support is 6.

8 0

3 years ago

The ball of a ballpoint pen is 0.5 mm in diameter and has an ASTM grain size of 12. How many grains are there in the ball

Fudgin [204]

Given :

The ball of a ballpoint pen is 0.5 mm in diameter and has an ASTM grain size of 12.

To Find :

How many grains are there in the ball?

Solution :

Volume of ball of the ballpoint is :

$V = \dfrac{4 \pi r^3}{3}\\\\V = \dfrac{4\times 3.14 \times 0.5^3}{3}\ mm^3\\\\V = 0.523\ mm^3$

Now, grain size of 12 has about 520000 grains/mm³.

Therefore, number of grains are :

$n = 520000\times 0.523\ grains\\\\n = 271960\ grains$

8 0

3 years ago

Is KBr a covalent or ionic compound

raketka [301]

Answer:

Ionic Compound

Explanation:

To identify the type of chemical bond in a molecule, look at the atoms that make up the compound. If there are two nonmetals, it is a covalent bond. If the two atoms are metals, it is a metallic bond. If one atom is a metal and the other is a nonmetal, it is an ionic bond. Ionic compounds are also known as salts. You can identify KBr as an ionic compound because potassium is a metal and a salt.

Hope this helps

6 0

3 years ago

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The fall of a body on the earth's surface cannot be a complete free fall why ?​

The fall of a body on the earth's surface cannot be a complete free fall why ?