how many continents do have in africa​

Answers

Answer 1

Answer:

There was 7 continents in africa


Related Questions

Compare the freezing point of water in the aquanaut’s apartment to its value at the surface. Is it higher, lower, or the same?

Answers

Answer:

Freezing Point - Lower

Boiling Point - Higher

Solid- liquid transition line in the phase diagram has a negative slope, but the liquid-gas transition line has a positive slope. Since there is more air pressure at 100m it will take less to freeze the water but more to boil it since it requires a larger temperature under larger pressures

Which pair of magnets has the strongest attraction between them?

Answers

I think it’s B. I apologize if I’m wrong.

what recommendations and coclusions can yiu make on the issue of human rights violation to Department of education ?​

Answers

I recommend that they chill out. After that, they can do a web search on the phrase "human rights." They will learn that it describes each particular person's political objectives, at least those who claim to be morally superior to everyone else.

A small block, with a mass of 0.05 kg compresses a spring with spring constant 350 N/m a distance of 4 cm. It is released from rest, then slides around the loop and up the incline before momentarily comes to rest at point A. The radius of the loop is 0.1 m.

Required:
Find the elastic potential energy.

Answers

Answer:

The elastic potential energy of the spring is 0.28 J

Explanation:

Given;

mass of the block, m = 0.05 kg

spring constant, k = 350 N/m

extension of the spring, x = 4 cm = 0.04 m

The elastic potential energy of the spring is calculated as;

[tex]U_x = \frac{1}{2}kx^2\\\\U_x = \frac{1}{2} \times 350 \times (0.04)^2\\\\U_x = 0.28 \ J[/tex]

Therefore, the elastic potential energy of the spring is 0.28 J

how to calculating critical angle for a glass and air interface when there is a total internal reflection between them.​

Answers

Answer:

total internal reflection

PLEASE HELP ME WITH THIS ONE QUESTION
The half-life of Barium-139 is 4.96 x 10^3 seconds. A sample contains 3.21 x 10^17 nuclei. How much of the sample is left after 1.98 x 10^4 seconds?

a) 8.03 x 10^16 nuclei

b) 4.01 x 10^16 nuclei

c) 2.02 x 10^16 nuclei

d) 1.61 x 10^17 nuclei

Answers

Answer:

c) 2.02 x 10^16 nuclei

Explanation:

The isotope decay of an atom follows the equation:

ln[A] = -kt + ln[A]₀

Where [A] is the amount of the isotope after time t, k is decay constant, [A]₀ is the initial amount of the isotope

[A] = Our incognite

k is constant decay:

k = ln 2 / Half-life

k = ln 2 / 4.96 x 10^3 s

k = 1.40x10⁻⁴s⁻¹

t is time = 1.98 x 10^4 s

[A]₀ = 3.21 x 10^17 nuclei

ln[A] = -1.40x10⁻⁴s⁻¹*1.98 x 10^4 s + ln[3.21 x 10^17 nuclei]

ln[A] = 37.538

[A] = 2.01x10¹⁶ nuclei remain ≈

c) 2.02 x 10^16 nuclei

An unruly student with a spitwad (a lump of wet paper) of mass 20 g in his pocket finds himself in the school library where there is a ceiling fan overhead. He relieves his boredom by throwing the spitwad up at the ceiling fan where it collides with, and sticks to, the end of one of the blades of the stationary ceiling fan. Its horizontal velocity vector is perpendicular to the long axis of the blade. If the fan is free to rotate (no friction at all) and has moment of inertia I=1.4kgm2 , if the spitwad has horizontal velocity 4 m/s, and if the spitwad sticks to the fan blade at a distance of 0.6 m from the rotation axis of the fan, how much time will it take the fan to move through one complete revolution after the spitwad hits it (closest answer)?

a. 1min
b. 2min
c. 3min
d. 4min
e. 5min
f. 6min

Answers

Answer:

T = 188.5 s, correct is  C

Explanation:

This problem must be worked on using conservation of angular momentum. We define the system as formed by the fan and the paper, as the system is isolated, the moment is conserved

         

initial instant. Before the crash

        L₀ = r m v₀ + I₀ w₀

the angular speed of the fan is zero w₀ = 0

final instant. After the crash

        L_f = I₀ w + m r v

        L₀ = L_f

        m r v₀ = I₀ w + m r v

angular and linear velocity are related

        v = r w

        w = v / r

        m r v₀ = I₀ v / r + m r v

         m r v₀ = (I₀ / r + mr) v

       v = [tex]\frac{m}{\frac{I_o}{r} +mr} \ r v_o[/tex]

let's calculate

       v = [tex]\frac{0.020}{\frac{1.4}{0.6 } + 0.020 \ 0.6 } \ 0.6 \ 4[/tex]

       v = [tex]\frac{0.020}{2.345} \ 2.4[/tex]

       v = 0.02 m / s

         

To calculate the time of a complete revolution we can use the kinematics relations of uniform motion

        v = x / T

         T = x / v

the distance of a circle with radius r = 0.6 m

         x = 2π r

we substitute

         T = 2π r / v

let's calculate

         T = 2π 0.6/0.02

         T = 188.5 s

reduce

         t = 188.5 s ( 1 min/60 s) = 3.13 min

correct is  C

2. Our solar system is made up of the Sun, 8 planets, and other bodies such as
asteroids orbiting the Sun. The solar system is very large compared to anything we see on
Earth. The distance between planets is measured in astronomical units (AU). One AU is
equal to 149.6 million kilometers, the average distance between the Sun and Earth. Scale
models are useful for helping us understand the size of the solar system.
Mr. Wilson’s science class made a scale model of the solar system. They went out to the
school’s football field, and they used the chart shown below to mark out the scale distance
from the Sun to each planet

Answers

It’s 25 because I already took the testing

a 1600 kg car rounds a curve of radius 71 m banked at an angle of 15, What is the magnitude of the friction force required for the car to travel at 86 km/h

Answers

Answer:

The frictional force required for the car to travel is 8,365.01 N

Explanation:

Given;

mass of the car, m = 1600 kg

radius of the curved road, r = 71 m

banking angle, θ = 15⁰

velocity of the car, v = 86 km/h = 86/3.6 = 23.89 m/s

The two forces acting on the are:

1.  the parallel force to the banked plane

2. the centripetal force pushing the car up the banked plane

To keep the car traveling at 86 km/h;

frictional force + parallel force to the plane = centripetal force pushing the car up the banked plane

The parallel force to the banked plane:

F = mgsinθ

F = 1600 x 9.8 x sin(15⁰)

F = 4,057.98 N

The centripetal force pushing the car up the banked plane:

[tex]F_c= (\frac{mv^2}{r} )cos(\theta)\\\\F_c = (\frac{1600 \times 23.89^2}{71} )cos(15^0)\\\\F_c = 12,422.99 \ N[/tex]

The frictional force required for the car to travel:

[tex]F_k = F_c - F\\\\F_k = 12,422.99 \ N - 4,057.98 \ N\\\\F_k = 8,365.01 \ N[/tex]

Therefore, the frictional force required for the car to travel is 8,365.01 N

A ratio that compares the width and length of a garden is what type of model?

Answers

Answer:

physical

PLEASE MARK ME AS A BRAINLIEST

Answer: Mathematical

Explanation: I took the quiz

PLEASE HELP ME WITH THIS ONE QUESTION
What is the rest energy of a proton? (c = 2.9979 x 10^9 m/s, mp = 1.6726 x 10^-27)

A) 8.18 x 10^-14 J

B) 2.73 x 10^-22 J

C) 1.5053 x 10^-10 J

D) 1.5032 x 10^-10 J

Answers

Answer:

djfjci3jsjdjdjdjdjddndn

ds

Calculating Acceleration
Initial
velocity
Time to travel
0.25 m
Final
velocity
Acceleration
Time to travel
0.50 m
# of
washers
11
(m/s)
V2
(m/s)
ti
(s)
t₂
(s)
a = (v2 - v4)/(t2-tı)
(m/s)
1
0.11
0.28
2.23
3.13
0.19
2
0.13
0.36
1.92
2.61
The acceleration of the car with two washers added to the string would be

Answers

I can not even read this question.

What are you trying to even say?

The acceleration of the car with two (2) washers added is equal to 0.33 [tex]m/s^2[/tex].

Given the following data:

Initial velocity = 0.13 m/s.Final velocity = 0.36 m/s.Initial time = 1.92 seconds.Final time = 2.61 seconds.

What is an acceleration?

An acceleration can be defined as the rate of change of velocity of an object with respect to time and it is measured in meter per seconds square.

How to calculate average acceleration.

In Science, the average acceleration of an object is calculated by subtracting its initial velocity from the final velocity and dividing by the change in time for the given interval.

Mathematically, average acceleration is given by this formula:

[tex]a = \frac{V\;-\;U}{t_f-t_i}[/tex]

Where:  

V is the final velocity.U is the initial velocity.[tex]t_i[/tex]initial time measured in seconds.[tex]t_f[/tex] final time measured in seconds.

Substituting the given parameters into the formula, we have;

[tex]a = \frac{0.36\;-\;0.13}{2.61\;-\;1.92}\\\\a=\frac{0.23}{0.69}[/tex]

a = 0.33 [tex]m/s^2[/tex]

Read more on acceleration here: brainly.com/question/24728358

calculate the voltage that is being applied across a 10W bulb if a current of 0.2A flows through it​

Answers

Answer:

below

Explanation:

from P= I * V

v = p/I

v = 10/0.2

v = 50 volts

The viscid silk produced by the European garden spider (Araneus diadematus) has a resilience of 0.35. If 10.0 J of work are done on the silk to stretch it out, how many Joules of work are released as thermal energy as it relaxes?

Answers

Answer: The energy released as thermal energy is 6.5 J

Explanation:

Energy stored by the spider when it relaxes is given by:

[tex]E_o=\text{Resilience}\times \text{Work}[/tex]

We are given:

Resilience = 0.35

Work done = 10.0 J

Putting values in above equation, we get:

[tex]E_o=0.35\times 10\\\\E_o=3.5J[/tex]

Energy released at thermal energy is the difference between the work done and the energy it takes to relaxes, which is given by the equation:

[tex]E_T=\text{Work done}-E_o[/tex]

Putting values in above equation, we get:

[tex]E_T=(10-3.5)=6.5J[/tex]

Hence, the energy released as thermal energy is 6.5 J

The energy released as thermal energy when 10 J of work is done to stretch silk will be 6.5 J

What is thermal energy?

Thermal energy refers to the energy contained within a system that is responsible for its temperature. Heat is the flow of thermal energy.

Energy stored by the spider when it relaxes is given by:

[tex]\rm E_o=Resilience \ \times Work[/tex]

We are given:

Resilience = 0.35

Work done = 10.0 J

Putting values in above equation, we get:

[tex]\rm E_o=0.35\times 10[/tex]

[tex]E_o=3.5\ J[/tex]

Energy released at thermal energy is the difference between the work done and the energy it takes to relaxes, which is given by the equation:

[tex]E_T=\rm Work done -E_o[/tex]

Putting values in above equation, we get:

[tex]E_T=(10-3.5)=6.5\ J[/tex]

Hence, the energy released as thermal energy is 6.5 J

To know more about thermal energy follow

https://brainly.com/question/19666326

Which type of energy is stored in a battery?
A. Nuclear energy
B. Electromagnetic energy
C. Chemical energy
D. Electrical energy
SUBMI

Answers

Answer:

c

Explanation:

in food and batteries chemical energy is stored :) hope this helped

an object is 70 um long and 47.66um wide. how long and wide is the object in km?​

Answers

Answer:

length =  7*10^(-8)km

width = 4.666*10^(-8) km

Explanation:

We know that:

1 μm = 1*10^(-6) m

and

1km = 1*10^3 m

or

1m = 1*10^(-3) km

if we replace the meter in the first equation, we get:

1 μm = 1*10^(-6)*1*10^(-3) km

1 μm = 1*10^(-6 - 3)km

1 μm = 1*10^(-9)km

Now with this relationship we can transform our measures:

Length: 70 μm is 70 times 1*10^(-9)km, or:

L = 70*1*10^(-9)km = 7*10^(-8)km

And for width, we have 47.66um, this is 46.66 times 1*10^(-9)km, or:

W = 46.66*1*10^(-9)km = 4.666*10^(-8) km

PLS HELP ME 100 POINTS PLS I NEED HELP QUICK PLS


For this project, you are expected to submit the following:
1. Your Student Guide with completed Student Worksheet
2. Your scale model of the solar system
Step 1: Prepare for the project.
a) Read through the guide before you begin so you know the expectations for this project.
b) If anything is not clear to you, be sure to ask your teacher.
Step 2: Conduct research on the actual sizes of the planets.
a) Do research to find the actual sizes of the Sun and the planets. This information is typically represented as diameter in kilometers (km). Recall that diameter is the length of the imaginary straight line from one side of a figure, such as a sphere, to the opposite side of the figure. This line passes through the center of the figure.
b) Record the actual diameters of the Sun and the planets in the first column of the table in the Student Worksheet.
c) Copy the link of the website you used into the space provided in the Student Worksheet.
Step 3: Determine the scaled sizes of the planets.
a) Go to a reliable website to find a solar system model calculator.
b) Decide how big you want the Sun in your model to be. For example, you could assign your Sun to be 300 mm. Input this figure in the calculator, and the calculator will determine the diameters of the eight planets for you. You want to make sure that the Sun is big enough so that the smallest planet will still be big enough to draw.
c) Record information from the calculator in the second column of the table in the Student Worksheet.
d) Copy the link of the website you used into the space provided in the Student Worksheet.
Step 4: Create a scale model of the solar system.
a) Draw and cut construction paper models of the Sun and the planets using the scaled measurements from the table.
b) Glue the models on the poster board. You can glue or tape poster boards together if necessary. Be sure to put the Sun in the center and to put the planets and a drawing of their orbits in order from nearest to farthest from the Sun.
Note: Remember that in this model, the diameter of the planets is scaled but the distance of the planets from the Sun is not. That means your model does not accurately represent the distances of the planets from the Sun so you need not worry about these measurements.
c) Label the Sun and the planets.
d) Put an attention-catching title above or below your model.
e) Write your name on the back of your poster board.
Step 5: Complete the Student Worksheet.
a) Make sure the table in the Student Worksheet is complete.
b) Answer the questions in the Student Worksheet.
c) Check to make sure you added the sources you used for this project in the Student Worksheet.
Step 6: Evaluate your project using this checklist.
If you can check each of the following boxes, you are ready to submit your project.
 Did you conduct research to find the actual size of the Sun and the planets? Did you record this information in the table in the Student Worksheet?
 Did you use a solar system model calculator to determine the scaled size of the Sun and planets? Did you record this information in the Student Worksheet?
 Did you add the links of the websites you used for this project to the Student Worksheet?
 Did you use the scaled sizes to create models of the Sun and the planets?
 Did you put your model together in a way that represents the solar system (Sun in the center and planets in order from nearest to farthest from the Sun)?
 Did you label each component of your model?
 Did you add an attention-catching title above or below your model?
 Did you write your name on the back of your poster board?
 Did you complete the Student Worksheet at the end of this guide?
Step 7: Revise and submit your project.
a) If you were unable to check off all the requirements on the checklist, go back and make sure that your project is complete. Save your project before submitting it.
b) Turn in your scale model of the solar system to your teacher. Be sure that your name is on it.
c) Submit your Student Guide through the virtual classroom.
d) Congratulations! You have completed your project.

Answers

Answer

I hope this help....

Explanation:

Answer:

Hope this helps

Explanation:

List and briefly explain the incidents leading to the occurrence of any five nuclear accidents that have taken place in different parts of the world.​

Answers

Answer:

Chernobyl Nuclear Disaster  Nuclear Disaster. Japan 2011  Kyshtym Nuclear Disaster. Russia 1957  Windscale Fire Nuclear Disaster. Sellafield, UK 1957 Three Mile Island Nuclear Accident. Pennsylvania, USA 1979

Explanation:

Hope this helps... pls vote as brainliest

A 3.25-gram bullet traveling at 345 ms-1 strikes and enters a 2.50-kg crate. The crate slides 0.75 m along a wood floor until it comes to rest.

Required:
a. What is the coefficient of dynamic friction between crate and the floor?
b. What is the average force applied by the crate on the bullet during collision if the bullet penetrates the 1.10cm into the crate?

Answers

Answer:

a)   μ = 0.0136, b)   F = 22.8 N

Explanation:

This exercise must be solved in parts. Let's start by using conservation of moment.

a) We define a system formed by the downward and the box, therefore the forces during the collision are internal and the momentum is conserved

initial instant. Before the crash

        p₀ = m v₀

final instant. After inelastic shock

        p_f = (m + M) v

the moment is preserved

        p₀ = p_f

        m v₀ = (m + M) v

        v = [tex]\frac{m}{m + M} \ v_o[/tex]

We look for the speed of the block with the bullet inside

        v = [tex]\frac{0.00325}{0.00325 + 2.50 } \ 345[/tex]

        v = 0.448 m / s

Now we use the relationship between work and kinetic energy for the block with the bullet

in this journey the force that acts is the friction

         W = ΔK

          W = ½ (m + M) [tex]v_f^2[/tex]  - ½ (m + M) v₀²

the final speed of the block is zero

the work between the friction force and the displacement is negative, because the friction always opposes the displacement

         W = - fr x

we substitute

           - fr x = 0 - ½ (m + M) vo²

           fr = ½ (m + M) v₀² / x

         

the friction force is

          fr = μ N

          μ = fr / N

equilibrium condition

          N - W = 0

          N = W

          N = (m + M) g

we substitute

         μ = ½ v₀² / x g

we calculate

          μ = ½ 0.448 ^ 2 / 0.75 9.8

          μ = 0.0136

b) Let's use the relationship between work and the variation of the kinetic energy of the block

          W = ΔK

initial block velocity is zero vo = 0

         F x₁ = ½ M v² - 0

         F = [tex]\frac{1}{2} M \frac{x}{y} \frac{v^2}{x1}[/tex]

         F = ½ 2.50 0.448² / 0.0110

         F = 22.8 N

according to the law of conservation of vhange , what must always be true in a nuclear reaction?​

Answers

Answer:

The Sum of mass and energy is always conserved in a nuclear reaction. Mass changes to energy, but the total amount of mass and energy combined remains the same

Explanation:

Every single radioactive decay, every single nuclear collision, every single nuclear reaction will conserve mass number and charge.

Electricity is the result of moving electrons, so it's classified as

A. Kinetic Energy
B. Gravitational Energy
C. Potential Energy
D. Elastic Energy

Answers

The answer should be A
The correct answer is A

identify the word being referred to choose your answer from the words below​

Answers

Answer:

1:Rotation

2:Axis

3:Aphelion

4:orbit

Answer in your PE notebook
I have learned that
I have realized that
I will apply

Answers

Answer:

physical science is important

hety

civil engineering

The power in an electrical circuit is given by the equation P= RR, where /is the current flowing through the circuit and Ris the resistance of the circuit. What is the current in a circuit that has a resistance of 100 ohms and a power of 15 watts?

[pleas ee helpppp)​

Answers

I= 0.39 A

OPTION B is the correct answer.

A sack of groceries with a mas of 22 kg is lifted off the floor with a velocity of 6 m/s. What is the kinetic energy of the sack
of groceries?

Answers

the answer is 396 joules :D

What is binding energy?

A.' The attractive forces between the protons in the nucleus and the

electrons

B. The energy required to force two nuclei to undergo nuclear fusion

C. The amount of energy stored in the strong nuclear forces of the

nucleus

D. The amount of energy required to overcome an activation energy

barrier

Please help me out.

Answers

Answer:

the answer is B i hope it helps :)

What is binding energy?

[tex]\huge\color{purple}\boxed{\colorbox{black}{♡Answer}}[/tex]

B. The energy required to force two nuclei to undergo nuclear fusion. ✅

They are usually expressed in terms of [tex]\sf\purple{kJ/mole}[/tex] of nuclei or [tex]\sf\pink{MeV's/nucleon}[/tex].

[tex]\large\mathfrak{{\pmb{\underline{\orange{Happy\:learning }}{\orange{!}}}}}[/tex]

PLEASE HELP ME WITH THIS ONE QUESTION
The half-life of Barium-139 is 4.96 x 10^3 seconds. A sample contains 3.21 x 10^17 nuclei. What is the decay constant for this decay?

A) 1.67 x 10^-4 s^-1

B) 5.43 x 10^-4 s^-1

C) 1.40 x 10^-4 s^-1

D) 2.22 x 10^-4 s^-1

Answers

OPTION C is the correct answer.

Kilometer is a unit of length where as kilogram is a unit of mass

Answers

By George, you've nailed it, Stacy !

That's a fact, uh huh.

Truer words were never written.

Your statement is one of unquestionable veracity.

The pure truthiness of it cannot be denied.

Was there a question you wanted to ask ?


Can somebody please help

Answers

Answer:

Explanation:

part A: C

part B: B

An astronaut throws a wrench in interstellar space. How much force is required to keep the wrench moving continuously with constant velocity?
A.
a force equal to its weight on Earth
B.
a force equal to zero
C.
a force equal to half of its weight on Earth
D.
a force equal to double its weight on Earth

Answers

Answer:

0 N

Explanation:

This is a trick question, the mass of the wrench would be 0 due to it being in space and has no gravitational pull to weight it down. And since acceleration is defined as the rate and change of velocity with no respect of time and the wrench is moving at a constant velocity, that means the velocity is 0. and since F = m*a it would be F = 0 * 0 = 0 N

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