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Yakvenalex [24]

2 years ago

12

Find a vector parametrization of the ellipse centered at the origin in the xy-plane that has major diameter 8 along the x-axis,

minor diameter 4 along the y-axis, and is oriented counter-clockwise. Your parametrization should make the point (4,0) correspond to t=0. Use t as the parameter in your answer.

1 answer:

Assoli18 [71]2 years ago

3 0

Answer:

E(t) = [ 4cos(t) , 2 sin(t) ]

Step-by-step explanation:

The elipse ecuacion is of the form:

(x² ÷ a² ) + (y² ÷ b² ) = 1 Where a and b are the horizontal and vertical semi-diameters respectively

In our particular case x²/16 + y²/ 4 = 1

That form suggests (x/a)² + (y/b)² =1

And again in our case x²/16 + y²/4 = 1 the same shape of sin²α +cos²α = 1

So we call x = 4 cos(t ) and the

We need to find y

x²/16 + y²/4 = 1

x²/16 + y²/4 = 1 ⇒ (x² + 4y²) ÷ 16 = 1

Solving for y (x² + 4y²) = 16 ⇒ y² = ( 16 - x²) ÷4

as x = 4 cos(t) ⇒ y² = (16 - 16cos²(t)) ÷ 4 y = √4 (1 -cos²(t)

y = 2 sin (t)

So the vector parametrization of the elipse is

E(t) = [ 4cos(t) , 2 sin(t) ]

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A bucket that has a mass of 30 kg when filled with sand needs to be lifted to the top of a 30 meter tall building. You have a ro

Rom4ik [11]

Answer:

765 J

Step-by-step explanation:

We are given;

Mass of bucket = 30 kg

Mass of rope = 0.3 kg/m

height of building= 30 meter

Now,

work done lifting the bucket (sand and rope) to the building = work done in lifting the rope + work done in lifting the sand

Or W = W1 + W2

Work done in lifting the rope is given as,

W1 = Force x displacement

W1 = (30,0)∫(0.2x .dx)

Integrating, we have;

W1 = [0.2x²/2] at boundary of 30 and 0

W1 = 0.1(30²)

W1 = 90 J

work done in lifting the sand is given as;

W2 = (30,0)∫(F .dx)

F = mx + c

Where, c = 30 - 15 = 15

m = (30 - 15)/(30 - 0)

m = 15/30 = 0.5

So,

F = 0.5x + 15

Thus,

W2 = (30,0)∫(0.5x + 15 .dx)

Integrating, we have;

W2 = (0.5x²/2) + 15x at boundary of 30 and 0

So,

W2 = (0.5 × 30²)/2) + 15(30)

W2 = 225 + 450

W2 = 675 J

Therefore,

work done lifting the bucket (sand and rope) to the top of the building,

W = 90 + 675

W = 765 J

5 0

2 years ago

A brochure from the department of public safety in a northern state recommends that motorists should carry 12 items (flashlights

scoray [572]

Answer:

$Mean = 6.07$

$Median = 7$

$Mode = 7$

Step-by-step explanation:

Given

$Data: 5\ 3\ 7\ 8\ 0\ 1\ 0\ 5\ 12\ 10\ 7\ 6\ 7\ 11\ 9$

$n = 15$

Solving (a): The mean

Mean is calculated as:

$Mean = \frac{\sum x}{n}$

This gives:

$Mean = \frac{5+ 3+ 7+ 8+ 0+ 1+ 0+ 5+ 12+ 10+ 7+ 6+ 7+ 11+ 9}{15}$

$Mean = \frac{91}{15}$

$Mean = 6.07$

Solving (b): The median

Sort the data in ascending order:

$Data: 5\ 3\ 7\ 8\ 0\ 1\ 0\ 5\ 12\ 10\ 7\ 6\ 7\ 11\ 9$

$Sorted: 0\ 0\ 1\ 3\ 5\ 5\ 6\ 7\ 7\ 7\ 8\ 9\ 10\ 11\ 12$

The median is:

$Median = \frac{n + 1}{2}th$

$Median = \frac{15 + 1}{2}th$

$Median = \frac{16}{2}th$

$Median = 8th$

The 8th item on the sorted dataset is 7; So:

$Median = 7$

Solving (c): The mode

$Mode = 7$

Because it has a frequency of 3 (more than any other element of the dataset).

6 0

2 years ago

Which expression has the same value as -18÷(-9)

erma4kov [3.2K]

Negative dividing by negative gives positive,
so 18:9=2

6 0

2 years ago

Read 2 more answers

A recent study found that 51 children who watched a commercial for Walker Crisps (potato chips) featuring a long-standing sports

hichkok12 [17]

Answer:

1

The claim is that the mean amount of Walker Crisps eaten was significantly higher for the children who watched the sports celebrity- endorsed Walker Crisps commercial

2

The kind of test to use is a t -test because a t -test is used to check if there is a difference between means of a population

3

$t = 3.054$

4

The p-value is $p-value = P(Z > 3.054) = 0.0011291$

5

The conclusion is

There is sufficient evidence to conclude that the mean amount of Walker Crisps eaten was significantly higher for the children who watched the sports celebrity- endorsed Walker Crisps commercial

The test statistics is

Step-by-step explanation:

From the question we are told that

The first sample size is $n_1 = 51$

The first sample mean is $\mu_1 = 36$

The second sample size is $n_2 = 41$

The second sample size is $\mu_2 = 25$

The first standard deviation is $\sigma _1 = 21.4 \ g$

The second standard deviation is $\sigma _2 = 12.8 \ g$

The level of significance is $\alpha = 0.05$

The null hypothesis is $H_o : \mu_1 = \mu_ 2$

The alternative hypothesis is $H_a : \mu_1 > \mu_2$

Generally the test statistics is mathematically represented as

$t = \frac{\= x_1 - \= x_2}{ \sqrt{ \frac{s_1^2}{n_1} + \frac{s_2^2}{n_2} } }$

=> $t = \frac{ 36 - 25}{ \sqrt{ \frac{ 21.4^2}{51} + \frac{ 12.8^2}{41} } }$

=> $t = 3.054$

The p-value is mathematically represented as

$p-value = P(Z > 3.054)$

Generally from the z table

$P(Z > 3.054) = 0.0011291$

=> $p-value = P(Z > 3.054) = 0.0011291$

From the values obtained we see that $p-value < \alpha$ so the null hypothesis is rejected

Thus the conclusion is

There is sufficient evidence to conclude that the mean amount of Walker Crisps eaten was significantly higher for the children who watched the sports celebrity- endorsed Walker Crisps commercial

5 0

2 years ago

Jaime finished analyzing a set of data with an explanatory variable x and a response variable y. He finds that the mean and stan

malfutka [58]

Answer:

The slope is m=2.145.

The y-intercept is b=-1.33.

Step-by-step explanation:

We have this data:

- The mean and standard deviation for x are 5.43 and 1.12, respectively.

- The mean and standard deviation for y are 10.32 and 2.69, respectively.

- The correlation is 0.893.

We have to calculate the slope and the y-intercept of the least-squares line.

With the given data, we can calculate the slope m as:

$m=r\;\dfrac{s_y}{s_x}=0.893\;\dfrac{2.69}{1.12}=2.145$

Then, the y-intercept is calculated as:

$b=\bar y-m\cdot \bar x=10.32-2.145\cdot 5.43=10.32-11.65=-1.33$

7 0

2 years ago