Ask question

Ask question

All categories

Nookie1986 [14]

3 years ago

9

A circular running track is 1/4 mile long. Elena runs on this track, completing each lap in 1/20 of an hour.What is Elena’s runn

ing speed? Explain your thinking

1 answer:

aniked [119]3 years ago

3 0

Answer:

Step-by-step explanation:

Answer:

Elena's running speed is 5 miles/hour

Explanation:

The speed is defined as the covered distance per unit time

In the problem, we have:

The distance covered is the length (circumference) of the circular track which is given as of a mile.

We are also given that she completes each lap (she completes of a mile) in of an hour

To get her speed, we will divide the distance covered by the time taken to cover this distance

This is done as follows:

speed = miles/hour

This means that:

Elena can run 5 miles each hour

Hope this helps :)

You might be interested in

ILL GIVE BRAINLEST, find the area of the square or rectangle. please show work :)

earnstyle [38]

99 is the area of the square

3 0

3 years ago

Read 2 more answers

The phone company Blurizon has a monthly cellular plan where a customer pays a flat fee for unlimited voice calls and then a cer

emmainna [20.7K]

Answer:

$y=2x+27$ .

Step-by-step explanation:

We have been given that when a customer uses 14 GB, the monthly cost will be $55. When the customer uses 38 GB, the monthly cost will be $103. We are asked to write an equation in slope-intercept form, where x is the number of GB of data used in a month and y is the total monthly cost of the Blurizon plan.

We have been given two points on line (14,55) and (38,103).

Let us find slope of line.

$m=\frac{103-55}{38-14}$

$m=\frac{48}{24}$

$m=2$

Now, we will use slope-intercept form of equation.

$y=mx+b$

$55=2(14)+b$

$55=28+b$

$55-28=28-28+b$

$b=27$

Therefore, our required equation would be $y=2x+27$ .

6 0

4 years ago

If f(x) = 5x²+2x-10, find f(6) - f (3)

vlada-n [284]

Answer:

681

Step-by-step explanation:

5x6=30

30x30=900

2x6=12-10=2

900+2=902

5x3=15

15x15=225

2x3=6

6-10=-4

225-4=221

902-221=681

8 0

4 years ago

The radius of the wheel on a bike is 21 inches. If the wheel is revolving at 154 revolutions per minute, what is the linear spee

Bezzdna [24]

Answer:

The linear speed of the bike is 19.242 miles per hour.

Step-by-step explanation:

If sliding between the bottom of the wheel and ground can be neglected, the motion of the wheel can be well described by rolling, which is a superposition of coplanar pure rotation and translation, The speed of the bike occurs at the center of the wheel, where resulting instantaneous motion is pure translation parallel to ground orientation. The magnitude of the speed of bike ( $v_{B}$ ), measured in inches per second, is:

$v_{B} = R\cdot \omega$

Where:

$R$ - Radius, measured in inches.

$\omega$ - Angular speed, measured in radians per second.

Now, the angular speed must be converted from revolutions per minute into radians per second:

$\omega = \left(154\,\frac{rev}{min} \right)\cdot \left(2\pi\,\frac{rad}{rev} \right)\cdot \left(\frac{1}{60}\,\frac{min}{s} \right)$

$\omega \approx 16.127\,\frac{rad}{s}$

The speed of the bike is: ( $R = 21\,in$ and $\omega \approx 16.127\,\frac{rad}{s}$ )

$v_{B} = (21\,in)\cdot \left(16.127\,\frac{rad}{s} \right)$

$v_{B} = 338.667\,\frac{in}{s}$

Lastly, the outcome is converted into miles per hour:

$v_{B} = (338.667\,\frac{in}{s} )\cdot \left(3600\,\frac{s}{h} \right)\cdot \left(\frac{1}{63360}\,\frac{mi}{in} \right)$

$v_{B} = 19.242\,\frac{mi}{h}$

The linear speed of the bike is 19.242 miles per hour.

5 0

4 years ago

A storage tank will have a circular base of radius r and a height of r. The tank can be either cylindrical or hemispherical (ha

Neko [114]

Answer:

Volume: $\frac{2}{3}\pi r^3$

Ratio: $\frac{2}{9}r$

Step-by-step explanation:

First of all, we need to find the volume of the hemispherical tank.

The volume of a sphere is given by:

$V=\frac{4}{3}\pi r^3$

where

r is the radius of the sphere

V is the volume

Here, we have a hemispherical tank: a hemisphere is exactly a sphere cut in a half, so its volume is half that of the sphere:

$V'=\frac{V}{2}=\frac{\frac{4}{3}\pi r^3}{2}=\frac{2}{3}\pi r^3$

Now we want to find the ratio between the volume of the hemisphere and its surface area.

The surface area of a sphere is

$A=4 \pi r^2$

For a hemisphere, the area of the curved part of the surface is therefore half of this value, so $2\pi r^2$ . Moreover, we have to add the surface of the base, which is $\pi r^2$ . So the total surface area of the hemispherical tank is

$A'=2\pi r^2 + \pi r^2 = 3 \pi r^2$

Therefore, the ratio betwen the volume and the surface area of the hemisphere is

$\frac{V'}{A'}=\frac{\frac{2}{3}\pi r^3}{3\pi r^2}=\frac{2}{9}r$

6 0

3 years ago