A woman jogs 20 km in 4 hours, then another 10 km in 2 hours. What is her average speed?

Nuclear fission is used for nuclear power plants because it produces what?

xenn [34]

It produces Heat Energy that can be used to drive steam turbines to generate Electricity.

4 0

3 years ago

Krishne wants to measure the mass and volume of a thimble. Which tools should she use?

andrew11 [14]

To measure the mass, you would use a balance. To measure the volume, you can use a variety of ounces, cups, pints, quarts, and gallons. Good luck!

6 0

3 years ago

Blood in a carotid artery carrying blood to the head is moving at 0.15 m/s when it reaches a section where plaque has narrowed t

sp2606 [1]

Answer:

26.9 Pa

Explanation:

We can answer this question by using the continuity equation, which states that the volume flow rate of a fluid in a pipe must be constant; mathematically:

$A_1 v_1 = A_2 v_2$ (1)

where

$A_1$ is the cross-sectional area of the 1st section of the pipe

$A_2$ is the cross-sectional area of the 2nd section of the pipe

$v_1$ is the velocity of the 1st section of the pipe

$v_2$ is the velocity of the 2nd section of the pipe

In this problem we have:

$v_1=0.15 m/s$ is the velocity of blood in the 1st section

The diameter of the 2nd section is 74% of that of the 1st section, so

$d_2=0.74d_1$

The cross-sectional area is proportional to the square of the diameter, so:

$A_2=(0.74)^2 A_1=0.548 A_1$

And solving eq.(1) for v2, we find the final velocity:

$v_2=\frac{A_1 v_1}{A_2}=\frac{A_1 (0.15)}{0.548 A_1}=0.274 m/s$

Now we can use Bernoulli's equation to find the pressure drop:

$p_1 + \frac{1}{2}\rho v_1^2 = p_2 + \frac{1}{2}\rho v_2^2$

where

$\rho=1025 kg/m^3$ is the blood density

$p_1,p_2$ are the initial and final pressure

So the pressure drop is:

$p_1 - p_2 = \frac{1}{2}\rho (v_2^2-v_1^2)=\frac{1}{2}(1025)(0.274^2-0.15^2)=26.9 Pa$

8 0

3 years ago

What is the density of a roll of pennies containing 50 pennies?

ololo11 [35]

Answer:

Density is defined as:

Density = Mass/Volume

Now, density is an intensive property, this means that if you have 10 grams of a given material or 1000 grams of the same material, in both cases you will find the same density.

Then a roll of 50 pennies has the same density that a single penny.

The measures of a single penny are:

Mass = 2.5 g

Thickness = 1.52 mm

Radius = 9.525 mm

The coin is a cylinder, and the volume of a cylinder is:

V = pi*r^2*h

where:

pi = 3.14

r = radius = 9.525mm

h = thikness = 1.52mm

The volume is:

V = 3.14*(9.525mm)^2*1.52mm = 433.015 mm^3

The density will be:

D = 2.5g/433.015mm^3 = 0.00577 g/mm^3

4 0

3 years ago

A force F with arrow= (5xî+ 4yĵ), where F with arrow is in newtons and x and y are in meters, acts on an object as the object mo

harkovskaia [24]

Answer:

w= 62.75 J

Explanation:

Given that

Force vector F= 5 x i + 4 y j

Space vector or displacement vector d= 5.01 i

We know that work (w)

w=∫ F.ds

w= ∫(5 x i + 4 y j) .dx ( only object is moving in x- direction)

$w=\int_{0}^{5.01}5xi.dxi$

$w=\int_{0}^{5.01}5x.dx$

$w=\left [\dfrac{5}{2}x^2\right ]_0^{5.01}$

w= 2.5 x 5.01² J

w= 62.75 J

6 0

2 years ago