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Trava [24]
3 years ago
10

You volunteer for chalkboard cleaning duty and you get to work with the erasers. As you rub the dust off of the chalkboard, whit

e chalk dust enters the air and makes you cough. As you clean the chalkboard with the eraser, are you causing a physical change or a chemical change? Explain your answer.
Physics
1 answer:
Anna71 [15]3 years ago
3 0

Answer:

A physical change

Explanation:

You are wiping chalk particles from the board to the eraser which is just changing the location of the chalk particles, a physical change.

you're not changing the chalk into a new substance or causing a chemical reaction, which would be a chemical change.

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Conveyor belts are often used to move packages around warehouses. The conveyor shown below moves packages at a steady 4.0 m/s. A
Alisiya [41]

Answer:

0 j

Explanation:

4 0
3 years ago
If a project team decided that a drugstore would earn the LT Credit—LEED for Neighborhood Development Location, what other Locat
DaniilM [7]

Answer:

None

Explanation:

It'll be impossible for the project to be eligible for any other LT credits because it can't double dip.

Double dip refers to obtaining money from two sources at the same time or by two separate accounting methods.

This is often regarded, unethical.

8 0
3 years ago
If the coefficient of friction is 0.3900 and the cylinder has a radius of 2.700 m, what is the minimum angular speed of the cyli
Aleks04 [339]

Answer:

w=3.05 rad/s or 29.88rpm

Explanation:

k = coefficient of friction = 0.3900

R = radius of the cylinder = 2.7m

V = linear speed of rotation of the cylinder

w = angular speed = V/R or to rewrite V = w*R

N = normal force to cylinder

N==\frac{m(V)^{2}}{R}=m*(w)^2*R

Friction force\\Ff = k*N\\Ff= k*m*w^2*R

Gravitational force \\Fg = m*g

These must be balanced (the net force on the people will be 0) so set them equal to each other.

Fg = Ff

m*g = k*m*w^2*R

g=k*w^{2}*R

w^2 =\frac{g}{k*R}

w=\sqrt{\frac{g}{k*R}} \\w =\sqrt{\frac{9.8\frac{m}{s^{2}}}{0.3900*2.7m}}\\ w=\sqrt{9.306}=3.05 \frac{rad}{s}

There are 2*pi radians in 1 revolution so:

RPM=\frac{w}{2\pi }*60\\RPM=\frac{3.05\frac{rad}{s}}{2\pi}*60\\RPM= 0.498*60\\RPM=29.88

So you need about 30 RPM to keep people from falling out the bottom

7 0
3 years ago
List atleast 10 applications of chemical effect of electric current
Komok [63]

Answer:

formation of gas bubbles at electrodes

deposition of metals at electrodes

changes in solution colour

electroplating

electrolysis

4 0
3 years ago
Estimate the wavelength of electrons that have been accelerated from rest through a potential difference of 60 kV.
ivolga24 [154]

Answer: 2.068*10^{-14}m

Explanation: According to work energy-theorem , the workdone in accelerating the electron equals the energy it would give off in terms of light.

workdone= qV

energy = hc/λ

q=magnitude of an electronic charge= 1.602*10^{-16}

h= planck constant = 6.626*10^{-34}

c= speed of light =2.998* 10^{8}

v= potential difference= 6*10^{4}

λ= wavelength=unknown

by making λ subject of formulae we have that

λ= \frac{hc}{qv}

λ = 6.626*10^{-34} * 2.998* 10^{8} / 1.602*10^{-16} * 6*10^{4}

λ = \frac{19.878*10^{-26} }{9.612*10^{-12} }

by doing the necessary calculations, we have that

λ = 2.068*10^{-14}m

8 0
3 years ago
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