Answer:
Atomic number of calcium is 20.
Why is friction a problem in space travellers
A bus starting from rest moves with a uniform acceleration of 0.1m/s2 for 2 minutes. Find (a)the speed acquired (b) the distance travelled
Answer:
a) 12m/s b) 720m
Explanation:
Use SUVAT:
a) u=0 a= 0.1 t= 2mins = 120 seconds v=?
v=u+at
v= 0 +(0.1*120)
v=12m/s
b) s=? u=0 a=0.1 t=120
s=ut+1/2at^2
s=0*120+1/2*0.1*120^2
s=720m
Why are car radiators painted black?
Answer:
To absorb heat
Explanation:
A black color is said to absorb much heat . This helps in cooling the engine as the radiator has absorbed the heat efficiently .
Additional Information:
A black object absorbs all wavelengths of light and reflects non , that is why it appears black .The more light an object absorbs , the more heat it absorbs .what is physical fitness? 1) the improvement of the body through inteninoal movement 2) the speed at which the body moves during exersize 3) the ability of the body to function of the body to function efficiently during exercise D) the preformence of mucles for long periods of time
Answer:
D) the preformence of mucles for long periods of time
Light is travelling through air reaches quartz at an angle of incidence of 35°. The index of refraction of quartz is 1.54. At what angle of refraction does the light travel into the quartz?
Answer:
1.54 = sin 35/sin r
sin r = 0.57/1.54 =0.37
r = sin^-1( 0.37)
=21.7°
A 4.0-kg ball has a momentum of 20.0 kg-m/s. What is the ball's speed?
Explanation:
Moving mass m = 4.0Kg
Momentum P = 20.0Kgm/s
Speed V = ?
Momentum = product of mass and its velocity
P = mV
V = P
m
V = 20
4
V = 5m/s
The ball's speed is 5 m/s.
What is speed?
Speed is distance travelled by the object per unit time. Due to having no direction and only having magnitude, speed is a scalar quantity With SI unit meter/second.
Given parameters:
Mass of the ball; m = 4.0Kg
Momentum of the ball; P = 20.0Kgm/s
We have to find; the speed of the ball; v = ?
We know that: Momentum of the ball = product of mass and its speed
⇒ P = mv
⇒ v = P/m
⇒ v = 20.0/4.0 m/s.
⇒ v = 5m/s
Hence, the speed of the ball is 5 m/s.
Learn more about speed here:
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How do power plants generate electricity?
Answer:
Explanation:
electrons are a waste product of bacteria living around plant roots – plants discharge organic matter into the soil, which is broken down by bacteria. It is possible to harvest them using motonless electrodes and turn them into electricity, without affecting the plant’s growth in any way.
write a sentence to describe how an image is formed on retina
when looking at distant objects.
Answer:
An image is formed on the retina with light rays converging most at the cornea and upon entering and exiting the lens. Rays from the top and bottom of the object are traced and produce an inverted real image on the retina. The distance to the object is drawn smaller than scale
Ella jogs down the street with a speed of 12 m/s. What is her kinetic energy if her mass is 58 kg?
Answer:
4176 J
Explanation:
Ella speed (V) = 12 m/s, Mass = 58 kg.
Kinetic energy of a body is the energy it possesses as a result of its motion. It is the energy (work) needed to cause a given body to move from rest to its final velocity. It is measured in Joules. The kinetic energy of a body is the same until its velocity changes.
Kinetic energy = 1/2 × m × V²
Kinetic energy = 0.5 × 58 × 12² = 4176 J
Two trains on parallel tracks are traveling in the same direction. One train starts 10 km behind the other. It overtakes the first train in 2 hours . What is the relative speed of the second train with respect to the first train?
Answer:
[tex]v'=v_2-v_1=5\frac{km}{h}[/tex]
Explanation:
The relative speed between the trains is given by:
[tex]v'=v_2-v_1[/tex]
v1: speed of the first train
v2: speed of the second train
To find the relative velocity you write the equation of motion of both train by taking into account the information of the statement. The trains have constant velocity. Furthermore, the second train stars 10 km behind the other one. hence you have:
[tex]x=10+v_1t\\\\x=v_2t[/tex]
for t = 2 hours, the positions of both trains are equal, thus you have:
[tex]10+v_1t=v_2t[/tex]
you factor v2 - v1 from the last equation and replace t = 2h:
[tex]10=v_2t-v_1t\\\\10=(v_2-v_1)t\\\\v_2-v_1=\frac{10}{t}=\frac{10}{2}=5 \frac{km}{h}[/tex]
Hence, you have that the relative velocity is:
[tex]v'=v_2-v_1=5\frac{km}{h}[/tex]
how light recats with each of diffrent types of space and materials
Answer:
Reflection is when light bounces off an object. If the surface is smooth and shiny, like glass, water or polished metal, the light will reflect at the same angle as it hit the surface. This is called specular reflection.
In a parallel circuit that has the same number and type of resistors as a series circuit the total resistance will be __________ and the total current will be ________. A.greater;greater B.lower;greater C.greater;the same D.the same;lower
Answer:
B. lower, greater
...............
Define 1 kg of mass as international standard
Answer:
1 kg is defined as the mass of a cylindrical Platinum iridium alloy whose height is equal to its diameter
Which statement about energy conservation BEST explains why a bouncing basketball will not remain in motion forever?
a The energy is used up and destroyed.
b The energy is transferred to light and potential energy.
c The energy is transformed to heat and chemical energy.
d The energy is transformed to sound and heat energy.
Answer:
d The energy is transformed to sound and heat energy.
Explanation:
Each time the basketball bounces, it makes sound waves, and dissipates energy in the form of heat in the material of the ball and the surrounding air. There is no light or chemical change involved.
Tear–free shampoos are advertised as having a pH similar to that of human tears. What pH would you expect tear–free shampoos to be?
Answer: 7
Explanation:
The pH of water, a neutral substance, is 7. Human tears are a saline composed mostly of water. Therefore, it stands to reason that a tear-free shampoo would have a similar pH close to 7.
Answer:
the pH level would be 7
Explanation:
7. A scientific theory can change if (2 points) nobody wants to believe it it becomes too old the scientist who discovered it dies we discover some new facts
Answer: this is true
Explanation: another one is if it is disproved
De acordo com a sequência de substâncias listada na tabela ao lado, se atritarmos vidro com lã, o vidro ficará carregado positivamente. Qual será a carga da madeira quando atritada com: a) lã b) seda c) marfim
Answer:
a) Wood is positively charged when rubbed with wool.
b) Wood is positively charged when rubbed with silk.
c) Wood is negatively charged when rubbed against ivory.
a) A madeira é carregada positivamente quando esfregada com lã.
b) A madeira é carregada positivamente quando esfregada com seda.
c) A madeira é carregada negativamente quando esfregada contra o marfim.
Explanation:
English Translation
According to the sequence of substances listed in the table opposite, if we rub glass with wool it will be positively charged. what will be the charge of the wood when rubbed with a) wool? b) silk? c) ivory?
Solution
What will happen when two materials are rubbed on each other is due to the sequence on the static electricity table, with the materials arranged based on their tendencies to rub off electrons from one another.
Materials lower on the table can rub off electrons from materials higher on the table, thereby making the higher material positively charged.
a) Wood and Wool
Wood is higher than wool on this table, hence, wool easily rubs off electrons from the surface of the wood and leaves the wood with an overall more positive charges. Wood is positively charged after this.
b) Wood and Silk
Wood is higher than silk on this table, hence, silk easily rubs off electrons from the surface of the wood and leaves the wood with an overall more positive charges. Wood is positively charged after this.
c) Wood and Ivory
Wood is lower than ivory on this table, Hence, wood rubs off electrons from the surface of the ivory material and the overall charges on the wood is more negative. Wood is negatively charged after this.
In Portugese/Em português
O que acontecerá quando dois materiais forem esfregados um no outro é devido à sequência na tabela de eletricidade estática, com os materiais organizados com base em suas tendências de esfregar elétrons um do outro.
Os materiais mais baixos da mesa podem remover elétrons dos materiais mais altos da mesa, tornando o material mais alto carregado positivamente.
a) Madeira e lã
A madeira é mais alta que a lã nesta tabela; portanto, a lã retira facilmente elétrons da superfície da madeira e deixa a madeira com uma carga geral mais positiva. A madeira é carregada positivamente depois disso.
b) Madeira e seda
A madeira é mais alta que a seda nesta tabela; portanto, a seda retira facilmente elétrons da superfície da madeira e deixa a madeira com uma carga geral mais positiva. A madeira é carregada positivamente depois disso.
c) Madeira e Marfim A madeira é mais baixa que o marfim nesta tabela. Portanto, a madeira elimina elétrons da superfície do material de marfim e as cargas gerais na madeira são mais negativas. A madeira é carregada negativamente depois disso.
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Espero que isto ajude!!!
How man significant figures does the following value gave 43.023
Answer:
It has 5 I hope this helps you
A mass of 15 X 10^5 kg is held at a position 9 m away from a mass of 20 X 10^6 kg. What is the gravitational attraction between the two masses?
Answer:
The gravitational attraction between the two masses is 24.7 N.
Explanation:
We have,
Mass of object 1, [tex]m_1=15\times 10^5\ kg[/tex]
Mass of object 2, [tex]m_2=20\times 10^6\ kg[/tex]
Distance between masses is 9 m
We know that there exists a gravitational force between masses when they are placed at certain distance. The gravitational force between masses is given by :
[tex]F=G\dfrac{m_1m_2}{r^2}\\\\F=6.67\times 10^{-11}\times \dfrac{15\times 10^5\times 20\times 10^6}{(9)^2}\\\\F=24.7\ N[/tex]
So, the gravitational attraction between the two masses is 24.7 N.
of the ball is
As the object falls off the roof of a tall building_______
turning into______
A) chemical potential energy; gravitational potential energy .
B) gravitational energy; kinetic energy .
C) chemical potential energy; kinetic energy.
D) kinetic energy ;gravitational potential energy.
Answer:b
Explanation:
velocity of a falling object increases.
so Kinetic energy of a falling object increases
height of a falling object from the ground decreases.
so the potential energy of a falling object decreases
indica el mecanismo de propagacion del calor en un liquido , gas , solido , vacio
Answer:
(See explanation below for further details)
Explanation:
(The following question is written in Spanish and for this purpose the answer will be written in such language).
1) La propagación del calor a través de sólidos, así como líquidos o gases en condiciones estacionarias se denomina conducción.
2) La propagación del calor a través de líquidos o gases en movimiento se denomina convección.
3) La propagación del calor a través del vacío o sin necesidad de un medio material se denomina radiación.
What does an electromagnet do?
Name five (5) things.
Answer:
it is used on hard disk drives, speakers, motors, mri machines, and generators
Explanation:
there ya go
Kepler’s third law states that for all objects orbiting a given body, the cube of the semimajor axis (A) is proportional to the square of the orbital period (P). For each of our planets orbiting the Sun, the relationship between the orbital period and semimajor axis can be represented by the equation P2 = kA3, where k is a constant value for all the planets. Rewrite this equation so that it solves for the constant of proportionality, k.
Explanation:
Kepler’s third law states that for all objects orbiting a given body, the cube of the semimajor axis (A) is proportional to the square of the orbital period (P).
For each of our planets orbiting the Sun, the relationship between the orbital period and semimajor axis can be represented by the equation as:
[tex]P^2=kA^3[/tex]
k is constant of proportionality
It is required to solve the above equation for k
[tex]k=\dfrac{P^2}{A^3}[/tex]
Answer:
k is constant of proportionality
It is required to solve the above equation for k
Explanation:
An artificial satellite is moving in a circular orbit of radius 42250 km. Calculate its speed if it takes 24 hours to revolve around the earth
Answer:
Distance covered by the satellite in 24 hours
s=2πr
=2×3.14×42250=265464.58 km
Therefore speed of satellite,
v = [tex]\frac{time taken}{distance travelled}[/tex]
= 24×60×60 /265464.58
=[tex]3.07 km s^{-1}[/tex] −
Explanation:
v= time taken /distance travelled
Identify each relationship as direct or inverse by choosing the correct answer from the drop-down menu.
speed of a car and the distance traveled
number of people at a party and the amount of food consumed
elevation above sea level and the air temperature
distance a planet is from the sun and the period of revolution
temperature of a bowl of soup and time
Intro
Done
ODODDDDDDD
5 of 9
Answer:
a) Direct
b) Direct
c) Inverse
d) Direct
e) Inverse
Explanation:
a) Speed of Car and Distance Traveled
Direct
Since, speed = (distance)(time)
Therefore, for constant time, Speed α Distance
b) No. of People at Party and Amount of Food Consumed
Direct
Since,
Food Consumed = (Food Consumed by 1 Person)(No. of People at Party)
Therefore, for constant amount of food consumed by 1 person,
Food Consumed α No. of People at Party
c) Elevation above Sea Level and Air Temperature
Inverse
The relation between altitude and air temperature is not constant. It changes in every layer of the atmosphere. So, if we only talk about the first layer, that is, Troposphere. Then the relation between elevation above sea level and air temperature is:
Air Temperature α 1/Elevation Above Sea Level
As, the elevation increases the air temperature decreases.
d) Distance of a Planet from Sun and Period of Revolution
Direct
According to Kepler's Law:
Period of Revolution α (Distance from Sun)^1.5
e) Temperature of a Bowl of Soup and Time
Inverse
Since, the initial temperature of soup is higher than the surrounding. Thus it loses heat to the surrounding with time. As a result the temperature of the soup decreases with time.
Therefore,
Temperature of Bowl of Soup α 1/Time
You decide to work at a heart rate of 150 instead of 120. What area of F.I.T.T. did you change?
Key concepts
Heart rate
Exercising
The heart
Cardiovascular system
Health
Introduction
As Valentine's Day approaches, we're increasingly confronted with "artistic" images of the heart. Real hearts hardly resemble to two-lobed shapes adorning cards and candy boxes this time of year. And the actual shape of the human heart is important for its function of supplying blood to the entire body. You have likely noticed that your heart beats more quickly when you exercise. But have you ever taken the time to observe how long it takes to return to its normal rate after you're done exercising? In this science activity you'll get to do some exercises to explore your own heart-rate recovery time.
Background
Your heart is continuously beating to keep blood circulating throughout your body. Its rate changes depending on your activity level; it is lower while you are asleep and at rest and higher while you exercise—to supply your muscles with enough freshly oxygenated blood to keep the functioning at a high level. Because your heart is also a muscle, exercise, in turn, helps keep it healthy. The American Heart Association recommends that a person does exercise that is vigorous enough to raise their heart rate to their target heart-rate zone—50 percent to 85 percent of their maximum heart rate, which is 220 beats per minute (bpm) minus their age for adults—for at least 30 minutes on most days, or about 150 minutes a week in total. So for a 20-year-old, the maximum heart rate would be 200 bpm, with a target heart-rate zone of 100 to 170 bpm. (For those 19 or younger, target zones can vary more than they do for adults.)
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Muitos remédios são tomados em doses menores que o mg. Um comprimido de certo remédio tem 0,025 mg de uma certa substância. Com 1 kg desta substância, quantos comprimidos podem ser feitos?
Answer:
Explanation:
The question is asked in portuguese
Hence, it will be answered in portuguese
1kg = 1000g
e
1 g = 1000mg
então
1 kg = 1 x (1000 x 1000)
1 kg = 1x 1.000.000
1 kg = 1.000.000mg
assim
1 comprimido -------------> 0,025 mg
x comprimido ------------> 1.000.000 mg ( só cruzar)
0,025(x) = 1(1.000.000)
0,025x = 1.000.000
x = 1.000.000/0,025
x = 40.000.000
1kg são feitos 40.000.000( Quarenta milhões de comprimidos)
Determining the pH of substances such as purple grape juice and catsup using test strips can be difficult. Why?
Answer:
Because they would naturally dye the test strips in the colors violet and red, regardless of their pH values
(would really appreciate the brainliest)
Answer:
they are naturally dark/dying the strips.
Explanation:
The distance that sound waves travel in a given amount of time
is the
of sound.
Answer:
Speed of Sound
Explanation:
what is the definition of the speed of sound?
The speed of sound can be defined as the distance that sound waves travel in a given amount of time
Sound travels at different speeds depending on what it is traveling through. Of the three mediums (gas, liquid, and solid) sound waves travel the slowest through gases, faster through liquids, and fastest through solids.
The speed of sound in dry air is 343 meters per second.
When the energy stored in the object is released it will turn into —————— energy.
Please fill in the blank.
Please someone answer this!! It’s my second time posting it!!!
Answer:
kinetic energy
Explanation:
Potential energy is stored energy.Kinetic energy is energy that a body possess as a result of its motion.
Gravitational potential energy is the energy stored in an object as the result of its height. The energy is stored as the result of the gravitational attraction of the Earth for the object