Ask question

Ask question

All categories

2 years ago

13

A girl skateboards with a kinetic energy of 2543.2 J. If the girl and skateboard have a total mass of 110kg , what is her speed

?

1 answer:

Mice21 [21]2 years ago

7 0

Answer:

6.8 Miles

Write at least 20 characters to explain it well.

You might be interested in

The price of a commodity has fell down by 15% so that priya can buy 3 more commodities for Rs 1700. What was the original price

erastova [34]

Answer:

2,000

Step-by-step explanation:

write out an equation that represents the problem. the original price X fell by 15% to a new price of 1700:

X - (X*15%) = 1700

X(1-0.15) =1700

X=1700/(1-0.15)

X=2,000

convert 15% to decimal form:

15%=0.15

7 0

2 years ago

If the sum of the zereos of the quadratic polynomial is 3x^2-(3k-2)x-(k-6) is equal to the product of the zereos, then find k?

lys-0071 [83]

Answer:

2

Step-by-step explanation:

So I'm going to use vieta's formula.

Let u and v the zeros of the given quadratic in ax^2+bx+c form.

By vieta's formula:

1) u+v=-b/a

2) uv=c/a

We are also given not by the formula but by this problem:

3) u+v=uv

If we plug 1) and 2) into 3) we get:

-b/a=c/a

Multiply both sides by a:

-b=c

Here we have:

a=3

b=-(3k-2)

c=-(k-6)

So we are solving

-b=c for k:

3k-2=-(k-6)

Distribute:

3k-2=-k+6

Add k on both sides:

4k-2=6

Add 2 on both side:

4k=8

Divide both sides by 4:

k=2

Let's check:

$3x^2-(3k-2)x-(k-6) \text{ with }k=2$ :

$3x^2-(3\cdot 2-2)x-(2-6)$

$3x^2-4x+4$

I'm going to solve $3x^2-4x+4=0$ for x using the quadratic formula:

$\frac{-b\pm \sqrt{b^2-4ac}}{2a}$

$\frac{4\pm \sqrt{(-4)^2-4(3)(4)}}{2(3)}$

$\frac{4\pm \sqrt{16-16(3)}}{6}$

$\frac{4\pm \sqrt{16}\sqrt{1-(3)}}{6}$

$\frac{4\pm 4\sqrt{-2}}{6}$

$\frac{2\pm 2\sqrt{-2}}{3}$

$\frac{2\pm 2i\sqrt{2}}{3}$

Let's see if uv=u+v holds.

$uv=\frac{2+2i\sqrt{2}}{3} \cdot \frac{2-2i\sqrt{2}}{3}$

Keep in mind you are multiplying conjugates:

$uv=\frac{1}{9}(4-4i^2(2))$

$uv=\frac{1}{9}(4+4(2))$

$uv=\frac{12}{9}=\frac{4}{3}$

Let's see what u+v is now:

$u+v=\frac{2+2i\sqrt{2}}{3}+\frac{2-2i\sqrt{2}}{3}$

$u+v=\frac{2}{3}+\frac{2}{3}=\frac{4}{3}$

We have confirmed uv=u+v for k=2.

4 0

2 years ago

Find the value of x.

hjlf

Answer:

x = 14

Step-by-step explanation:

Since they are similar triangles, their sides are proportional

12 : 15 :: 8 : x - 4

Product of extremes = Product of means

12 × ( x- 4 ) = 15 × 8

12x -48 = 120

12x = 120 + 48

12x = 168

x = 168/12

x = 14

6 0

2 years ago

The coordinates of three vertices of square ABCD are A(−212,112),B(−212,−3), and C(2,112).

Lady_Fox [76]

Answer:

<em>P=760</em>

Step-by-step explanation:

Three of the coordinates of the square ABCD are A(-212,112) B(-212,-3) C(2,112). The image below shows the square is not ABCD but ABDC. In fact, this is not a square, as we'll prove later.

Note the x-coordinate of A and B are the same. It means this side is parallel to the y-axis. Also, the y-coordinate of A and C are the same, meaning this side is parallel to the x-axis. The missing point D should have the same x-coordinate as C and y-coordinate as B, i.e. D=(2,-3).

This shape has sides that are parallel to both axes.

To calculate the perimeter we find the length of two sides.

The distance from A to B is the difference between their y-axis:

w=112-(-3)=115

The distance from A to C is the difference between their x-axis:

l=2-(-212)=215

It's evident this is not a square but a rectangle. The perimeter is

P=2w+2l=330+430

P=760

7 0

2 years ago

You download 12 new songs to your MP3 player. Then you delete 5 old songs. Write each amount as an integer.

Lapatulllka [165]

Answer:

the new ones and the old ones that you didn’t delete

Step-by-step explanation:

5 0

2 years ago