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3 years ago

Why is an element considered a pure substance?

Physics

1 answer:

anastassius [24]3 years ago

3 0

Answer:

An element is a pure substance and is made of only one type of atom.

Explanation:

It cannot be broken down into a simpler substance.

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A 79 kg person sits on a 3.7 kg chair. Each leg of the chair makes contact with the floor in a circle that is 1.3 cm in diameter

vampirchik [111]

I'll assume that the chair has four legs.

Since the chair weights 3.7 kg by itself, it will weigh (79+3.7)=82.7 kg with the person sitting on it. And each of the chair's legs will take about (82.7/4)=20.675 kg.

Each leg touches the floor in a circle with 1.3cm diameter. The area of that circle is about (3.14*(1.3/2)^2)=1.327 cm^2.

Pressure is measured by force per area. So, the pressure from each leg is about 20.675kg / 1.327cm^2. That simplifies to 15.58 kg/cm^2.

7 0

3 years ago

When calculating the net electrostatic force, a negative value indicates that the two charged objects involved __________.

DiKsa [7]

Answer:

Explanation:

The correct answer is B) have unlike charges. Since they are attracted to each other they have to be unlike

5 0

3 years ago

A mass of 10 g of oxygen fill a weighted pistonâ€“cylinder device at 20 kPa and 110Â°C. The device is now cooled until the tempe

mezya [45]

Answer:

The change of the volume of the device during this cooling is $14.3\times10^{-3}\ m^3$

Explanation:

Given that,

Mass of oxygen = 10 g

Pressure = 20 kPa

Initial temperature = 110°C

Final temperature = 0°C

We need to calculate the change of the volume of the device during this cooling

Using formula of change volume

$\Delta V=V_{2}-V_{1}$

$\Delta V=\dfrac{mR}{P}(T_{2}-T_{1})$

Put the value into the formula

$\Delta V=\dfrac{0.3125\times0.0821}{2.0265\times10^{9}}(383-273)$

$\Delta V=14.297\ L$

$\Delta V=14.3\times10^{-3}\ m^3$

Hence, The change of the volume of the device during this cooling is $14.3\times10^{-3}\ m^3$

6 0

3 years ago

Two identical charges q placed 2.0 mapart exert forces of magnitude 4.0 N on each other What is the value of the charge q? a) q

katen-ka-za [31]

Answer:

c) $4.2*10^{-5}C$

Explanation:

Coulomb's law says that the force exerted between two charges is inversely proportional to the square of distance between them, and is given by the expression:

$F=\frac{kq_{1}q_{2}}{r^{2}}$