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barxatty [35]
2 years ago
13

How is energy involved in physical change??

Mathematics
1 answer:
tensa zangetsu [6.8K]2 years ago
3 0

Answer:during phase chages

Step-by-step explanation:

During phase changes, energy changes are usually involved. For example, when solid dry ice vaporizes (physical change), carbon dioxide molecules absorb energy. When liquid water becomes ice, energy is released. Remember that all chemical reactions involve a change in the bonds of the reactants

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If x2 = 30, what is the value of x?<br> A. ±60 B. ±15 C. ±square root of 30 D.±square root of 15
anygoal [31]

Answer:

  C.  ±square root of 30

Step-by-step explanation:

Apply the square root function to both sides of the equation:

  \sqrt{x^2}=\sqrt{30}\\\\|x|=\sqrt{30}\\\\x=\pm\sqrt{30}

_____

The absolute value equation has two solutions. They match choice C.

6 0
3 years ago
HELP: I need help on multiple questions for a quiz before tomorrow night. If all is answered, you will get 40+ points and marked
Vinil7 [7]

Answer:

1.  $33,000

2.  $6077.53

3.

a)  2.72 seconds

b)  0.96 seconds

4.  189 square meters

5.

a)  Average Rate of Change = 4 pounds per week, or -4

b)  160 pounds (after 5 weeks)

6.  

Independent Variables = p, A, and H

Dependent Variable = T

141 beats per minute (rounded to nearest whole number)

Step-by-step explanation:

1.

The value of a tractor V(t) decreases over time, t. Its value is given by:

V(t)=55000-5500t

To find value of tractor after 4 years, we would need to substitute "4" into t and calculate. It is shown below:

V(t)=55000-5500t\\V(4)=55000-5500(4)\\V(4) =33000

The value of the tractor after 4 years is <u>$33,000</u>

<u></u>

2.

The value of investment that is growing each year, is given by:

f(n)=5000(1.05)^{n}

Where

5000 is the initial investment (deposit)

1.05 means a 5% growth rate per year

n is the time in years

We want the investment's value after 4 years, so n would be 4. Substituting we get our answer:

f(n)=5000(1.05)^{n}\\f(4)=5000(1.05)^{4}\\f(4)=6077.53

To the nearest cent, the value of the investment would be:

<u>$6077.53</u>

<u></u>

3,

The time it takes of pendulum to make one swing is given by the formula:

T(L)=2\pi \sqrt{\frac{L}{32}}

Where L is the length of the pendulum in feet

a)

If L = 6ft, the time it will take is:

T(6)=2\pi \sqrt{\frac{6}{32}}\\T(6)=2.72

About <u>2.72 seconds</u>

<u></u>

b)

Now, the length is 9 inches, we convert it to feet first:

9/12 = 0.75 feet

So, the time it will take:

T(0.75)=2\pi \sqrt{\frac{0.75}{32}}\\T(0.75)=0.96

So, it will take about <u>0.96 seconds</u>

<u></u>

4.

The area of weed after t days can be modeled by:

A(t)=0.006 \pi t^2

Where t is number of days

Now, we want to find area after 100 days, so let t = 100, we get:

A(t)=0.006 \pi t^2\\A(100)=0.006 \pi (100)^2\\A(100)=188.5

Rounded to nearest sq. m, we have the area to be:

<u>189 square meters</u>

<u></u>

5.

a)

The avg. rate of change is basically how much the program is advertising that someone can loose in a week. It says "4 pounds per week". Since decrease, we give the value of "4" and negative sign So:

<u>Average Rate of Change = 4 pounds per week, or -4</u>

<u></u>

b)

Initial weight is 180 pounds, we know 4 pounds is decreased every week when going through the program course. So, after 5 weeks,

5 * 4 = 20 pounds will be less

So, he will be:

180 - 20 = <u>160 pounds (after 5 weeks)</u>

6.

The Karvonen formula is given as:

T=p(220-A)+H(1-p)

Where

T is target heart rate (in bpm)

p is the percent intensity (expressed as decimal)

A is the age (in yrs)

H is the resting heart rate (in bpm)

We need to identity the independent and dependent variables. Now, lets that a simple example:

y = 2x

Here,

x is the independent variable

y is dependent on x, so y in dependent

Similarly, if you look at the formula, you can see:

p, A, and H are all independent

T depends on them

So,

p, A, H are independent variables

T is the dependent variable

<u>Independent Variables = p, A, and H</u>

<u>Dependent Variable = T</u>

<u></u>

We are given

A = 35

H = 60

p = 65% = 65/100 = 0.65

Now, we want T, lets substitute and find:

T=0.65(220-35)+60(1-0.65)\\T=141.25

<u>The target heart rate should be:  141 beats per minute (rounded to nearest whole number)</u>

<em><u /></em>

<em><u /></em>

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Step-by-step explanation:

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