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3 years ago

9

People who hunt animals, go fishing, and gather fruits, nuts, roots, berries, and other parts of plants that can be used as food

are called:

1 answer:

Masja [62]3 years ago

7 0

Native American I think in not sure

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Zoe is shown two mystery boxes that are both 8,000cm3. Her teacher tells her that one mystery box is filled with rocks and the o

krek1111 [17]

Answer:

The box of rocks will have depression which can be seen without touching the box.

Explanation:

The density of rocks is very large as compared with napkins. So, the weight of the rocks will be much more greater than that of napkins.

As both boxes have same volume the heavier box will show depression on the lower surface as compared to the lighter box. So, the box of rocks will have depression which can be seen without touching the box.

5 0

3 years ago

What must happen to the electrons in a material to create an electric current?

photoshop1234 [79]

Electric current is a stream of electrons in motion, so they have to gain an energy from outside. There are two possibilities: one of them is the photoeletric phenomenom which is based on striking electrons from their orbits with the photon's energy. Second options is the substraction od eletric potentials on the edges od material.

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3 years ago

A person walking in high heals can damages the floor by making small dimples in the floor since all their weight is concentrated

iren [92.7K]

Given :

Mass of person, m = 81 kg.

Area of high heal, A = 3.5 cm² = 0.00035 m².

To Find :

The pressure applied by the heal on the ground.

Solution :

We know, pressure is given by :

$P = \dfrac{mass}{Area}\\\\P = \dfrac{81}{0.00035} \ N/m^2\\\\P = 231428.57 \ N/m^2$

Hence, this is the required solution.

4 0

3 years ago

Although the evidence is weak, there has been concern in recent years over possible health effects from the magnetic fields gene

Natasha2012 [34]

Answer:

A. $B = 6.36 * 10^{-10} T$

B. P ≈ 0

Explanation:

In order to calculate the magnetic field strength we have to use the magnetic field strength of a straight wire.

$B = \frac{mi* I}{2\pi *d}$ (eq. I)

B = magnetic field strength at distance d

I = current (A)

mi = represented by the greek letter μ, represents the permeability of the free space, which is: 4 × π 10^(-7) T m/A

d = distance from the wire

By replacing the values in eq I, we have the following:

$B = \frac{4\pi 10^{-7} T m A^{-1} 200 A}{2\pi *20 m}\\\\B = 6.36 * 10^{-10} T\\$ (eq II)

The earth magnetic field in the surface variates from 25 to 65 microteslas. Thus:

P = Percentage from the wires/percentage of the earth

$P = \frac{6.36 * 10^{-10}T}{65* 10^{-3} T}\\$ ∵ $B$ ∴

P ≈ 0

5 0

4 years ago

Assume you need to design a hydronic system that can deliver 80,000 Btu/hr. What flow rate of water is required if the temperatu

PolarNik [594]

Answer:

At 10°F change in temperature

Mass flowrate = 1.01 kg/s = 2.227 lbm/s

Volumetric flowrate = 1010 m³/s = 35667.8 ft³/s

At 20°F change in temperature

Mass flowrate = 0.505 kg/s = 1.113 lbm/s

Volumetric flowrate = 505 m³/s = 17833.9 ft³/s

Explanation:

80000 btu/hr = 23445.7 W

P = ṁc(ΔT)

ṁ = MASS flowrate

c = specific heat capacity of water = 4182 J/kg.K,

ΔT = change in temperature = 10°F

To convert, a change of 18°F is equal to a change of 10°C

A change of 10°F = 10×10/18 = 5.556°C = 5.556K

P = ṁc(ΔT)

23445.7 = ṁ(4182 × 5.556)

ṁ = 23445.7/(4182 × 5.556)

ṁ = 1.01 kg/s = 2.227 lbm/s

In volumetric flow rate, Q = density × mass flowrate = 1000 × 1.01 = 1010 m³/s = 35667.8 ft³/s

For a change of 20°F,

ΔT = change in temperature = 20°F

To convert, a change of 18°F is equal to a change of 10°C

A change of 20°F = 20×10/18 = 11.1111°C = 11.111K

P = ṁc(ΔT)

23445.7 = ṁ(4182 × 11.111)

ṁ = 23445.7/(4182 × 11.111)

ṁ = 0.505 kg/s = 1.113 lbm/s

In volumetric flow rate, Q = density × mass flowrate = 1000 × 0.505 = 505 m³/s = 17833.9 ft³/s

Hope this Helps!!!

4 0

3 years ago