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diamong [38]
3 years ago
5

Expand (2x + y) (2x - y).​

Physics
1 answer:
KiRa [710]3 years ago
8 0

Answer: 4x²-y²

Explanation:

FORMULA

a²-b²=(a+b)(a-b)

-----------------------------

(a+b)(a-b)=a²-b²

(2x+y)(2x-y)=(2x)²-(y)²

                  =4x²-y²

Hope this helps!! :)

Please let me know if you have any question

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Which best describes cosmic microwave background radiation? radiation thought to exist but not yet measured radiation predicted
grigory [225]

Answer:  leftover radiation from the big bang

Microwave background radiation is a form of electromagnetic radiation that is present in the whole universe and completely fills it.

Its frequency belongs to the microwaves range and is one of the main demonstrations of the of the Big Bang theory model.

It is important to note the Big Bang occurred 400,000 years before the events related to the microwave cosmic radiation, this means the Big Bang occurred first.

8 0
3 years ago
A tradesman sharpens a knife by pushing it with a constant force against the rim of a grindstone. The 30-cm-diameter stone is sp
Lorico [155]

Answer:

a. 0.21 rad/s2

b. 2.205 N

Explanation:

We convert from rpm to rad/s knowing that each revolution has 2π radians and each minute is 60 seconds

200 rpm = 200 * 2π / 60 = 21 rad/s

180 rpm = 180 * 2π / 60 = 18.85 rad/s

r = d/2 = 30cm / 2 = 15 cm = 0.15 m

a)So if the angular speed decreases steadily (at a constant rate) from 21 rad/s to 18.85 rad/s within 10s then the angular acceleration is

\alpha = \frac{\Delta \omega}{\Delta t} = \frac{21 - 18.85}{10} = 0.21 rad/s^2

b) Assume the grind stone is a solid disk, its moment of inertia is

I = mR^2/2

Where m = 28 kg is the disk mass and R = 0.15 m is the radius of the disk.

I = 28*0.15^2/2 = 0.315 kgm^2

So the friction torque is

T_f = I\alpha = 0.315*0.21 = 0.06615 Nm

The friction force is

F_f = T_f/R = 0.06615 / 0.15 = 0.441 N

Since the friction coefficient is 0.2, we can calculate the normal force that is used to press the knife against the stone

N = F_f/\mu = 0.441/0.2 = 2.205 N

7 0
3 years ago
The asteroid 2007 VK184 has one chance in 2940 of hitting the Earth between the years 2048 and 2057. The asteroid is 130 meters
N76 [4]

Answer:

 The average death rate for this type of event is closest to 350 people per event.

Explanation:

Between the years 2048 and 2057

Is 10 years. Since there is only one chance of event between these years, there is no point to consider it.

The total number of events = 2940 chances.

average death rate per event = total number of dead people divided by total number of events of occurrence.

1000000/2940 = 340.134

The average death rate for this type of event is therefore closest to 350 people per event

4 0
3 years ago
What does 3F means?<br><br>Please help me with this.....​
Debora [2.8K]

Answer: Fitness, Fun & Friendship

Explanation:

5 0
3 years ago
Why is a warm, tropical cumulus cloud more likely to produce precipitation than a cold, stratus cloud?
Lelu [443]

Explanation:

Warm,tropical cumulus cloud more likely to produce precipitation because they have high liquid content, strong and consistent updraft, these clouds are very thick. Moreover, they have large range of cloud droplet sizes. Whereas, stratus cloud have somewhat opposite characteristics, hence tropical cumulus clouds produce more precipitate.  

7 0
3 years ago
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