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3 years ago

11

PLZZZ HURRY a student is performing experiments on a particular substance which statement is an observation of a chemical proper

ty of the substance
a- it sinks WILL MARK BRAINLEST PLZZZZ HURRY
b-it freezes
c-it reacts with air
d- its viscosity increases

2 answers:

Katena32 [7]3 years ago

7 0

It’s d all the other answer would not be a chemical property

Scilla [17]3 years ago

5 0

Answer:

C it reacts with air

Explanation:

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4 years ago

a fan acquires a speed of 180 rpm in 4s, starting from rest. calculate the speed of the fan at the end of the 5th second startin

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Answer:

225 rpm

Explanation:

The angular acceleration of the fan is given by:

$\alpha = \frac{\omega_f - \omega_i}{\Delta t}$

where

$\omega_f$ is the final angular speed

$\omega_i$ is the initial angular speed

$\Delta t$ is the time interval

For the fan in this problem,

$\omega_i = 0\\\omega_f = 180 rpm\\\Delta t=4 s$

Substituting,

$\alpha = \frac{180-0}{4}=45 rpm/s$

Now we can find the angular speed of the fan at the end of the 5th second, so after t = 5 s. It is given by:

$\omega' = \omega_i + \alpha t$

where

$\omega_i = 0\\\alpha = 45 rpm/s\\t = 5 s$

Substituting,

$\omega' = 0 + (45)(5)=225 rpm$

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3 years ago

You are planning to make an open rectangular box from an 8-inch by 15-inch piece of cardboard by cutting congruent squares from

Phoenix [80]

Let us say that x is the cut that we will make on the sides to make a box, therefore the new dimensions are:

l = 15 – 2x

w = 8 – 2x

It is 2x since we cut on two sides.

We know that volume is:

V = l w x

V = (15 – 2x) (8 – 2x) x

V = 120x – 30x^2 – 16x^2 + 4x^3

V = 120x – 46x^2 + 4x^3

Taking the 1st derivative:

dV/dx = 120 – 92x + 12x^2

Set dV/dx = 0 to get maxima:

120 – 92x + 12x^2 = 0

Divide by 12:

x^2 – (92/12)x + 10 = 0

(x – (92/24))^2 = -10 + (92/24)^2

x - 92/24 = ±2.17

x = 1.66, 6

We cannot have x = 6 because that will make our w negative, so:

x = 1.66 inches

So the largest volume is:

V = 120x – 46x^2 + 4x^3

V = 120(1.66) – 46(1.66)^2 + 4(1.66)^3

V = 90.74 cubic inches

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4 years ago

An electrician timed a box traveling over a conveyor and measured 25 sec to travel 30 feet. If the gearbox ratio is 20:1 and the

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4 years ago

A starship travels to a planet that is 20 light years away. The astronauts stay on the planet for 2.0 years before returning at

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Answer:

astronauts age is 32 years

correct option is e 32 years

Explanation:

given data

travels = 20 light year

stay = 2 year

return = 52 years

to find out

astronauts aged

solution

we know here they stay 2 year so time taken in traveling is

time in traveling = ( 52 -2 ) = 50 year

so it mean 25 year in going and 25 years in return

and distance is given 20 light year

so speed will be

speed = distance / time

speed = 20 / 25 = 0.8 light year

so time is

time = $\frac{t}{\sqrt{1-v^2} }$

time = $\frac{25}{\sqrt{1-0.8^2} }$

time = 15 year

so age is 15 + 2 + 15

so astronauts age is 32 years

so correct option is e 32 years

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3 years ago