Answer:
29.41%
Explanation:
Given that,
In 1630 at the beginning of European settlement, about 425,000,000 hectares of the United States were covered with trees.
By 2017, the area covered by trees was reduced to 300,000,000 hectares.
We need to find the percentage decrease in the area covered by trees between 1630 and 2017.
The percentage decrease in any value is given by :
[tex]\%=\dfrac{300,000,000 -425,000,000 }{425,000,000 }\times 100\\\\=29.41\%[/tex]
So, the percentage decrease in the area covered by the trees is 29.41%.
A 2.0 kg block is pulled across a horizontal surface by a 15 N force at a constant velocity.a. What is the net force acting on the block?
Answer:
0
Explanation:
the block is being pulled at a constant velocity meaning it has no acceleration. the rule is fnet=mass x acceleration so if theres no acceleration there is no force net!
A block of mass 2 kg is pulled across a surface with a force of 15 N then the net force acting on the block is 0.
What is Force?A force is an effect that can alter an object's motion according to physics. A force might cause an object has mass to accelerate when it changes its velocity, for, us when it moves away from rest. An obvious way to describe force is in terms of push or pull. A force is a vector quantity since it has equal magnitude and direction. It is calculated using the newton SI unit (N). Force is denoted by the letter F.
The net force exerted by an object was equal to the speed at which its velocity varies over time, according to Newton's second law in its original formulation.
The block has no acceleration because it is being pushed at a constant speed. If there is no acceleration, there is no force net because the formula is net force =mass × acceleration.
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Which of the following can sometimes be zero for a moving body i average velocity ii distance travelled iii average speed iv displacement
Answer:
displacement can be zero...because it only care about initial and final positionsWhat is radioactive dating? How is it used to determine age of something?
answer 2 question basically please Help!!!
Answer:
Technique of comparing abundance ratio between radioactive isotopes to a reference isotope to determine the age of a material called radioactive dating. It determines the age by having a more abundance of isotopes in the cellular being.
what does a steep slope line mean? in science
Answer:
Simply put, slope refers to the steepness of a line. The larger the slope, the steeper the line. Slope is often referred to as 'rise over run' because it is calculated by the change in the vertical (rise) divided by the change in the horizontal (run). ... For example, a high value of slope means a very steep line.
A force has both______ and _______. Question 3 options: Magnitude & Direction Direction & Motion Speed & Impact Speed and Direction
Answer:
A force has both Direction and Motion.
Explanation:
For example, when finding acceleration you take the time and divided it by distance. If the thing you are measuring is going in the positive direction, the acceleration will be positive and if it is going in the negative direction the acceleration will be negative.
Magnitude and Direction
Explanation:
Force is a Vector Quantity
As learned in an earlier unit, a vector quantity is a quantity that has both magnitude and direction. To fully describe the force acting upon an object, you must describe both the magnitude (size or numerical value) and the direction.
explain why smoke particles in air move about faster if the temp of the air is increased??
Answer:
kinetic energy increases with the energy which causes the particles to move faster resulting in increases collision rates and rate of diffusion.
Explanation:
The increase in temperature of the air causes the air molecules to have more kinetic energy, which leads to more frequent and forceful collisions with the smoke particles. This, in turn, causes the smoke particles to move faster through the air.
What is kinetic energy?Kinetic energy is the energy an object possesses due to its motion. Any object that is in motion has kinetic energy, and the amount of kinetic energy it has depends on its mass and velocity.
The formula for calculating kinetic energy is:
KE = 1/2 × m × v²
where KE represents kinetic energy, m represents the mass of the object, and v represents the velocity of the object.
Here in the question,
Smoke particles in the air move around due to collisions with air molecules. When the temperature of the air increases, the average kinetic energy of the air molecules also increases. This means that the air molecules are moving faster and colliding more frequently with the smoke particles.
The smoke particles themselves do not have an increase in kinetic energy, but they do receive more energy from the collisions with the air molecules. This extra energy causes the smoke particles to move faster and more erratically, making them more dispersed throughout the air.
In addition, when air is heated, it becomes less dense. This means that there are fewer air molecules in a given volume of air. As a result, the smoke particles have more space to move around and collide with air molecules, which further contributes to their increased speed and movement.
Therefore, increasing the temperature of the air increases the speed and frequency of collisions between the air molecules and smoke particles, leading to the smoke particles moving faster and more widely dispersed throughout the air.
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A horizontal net force is exerted on a 2.0 kg object at rest. The object starts at x=0 m and travels 8.0 m along a horizontal frictionless surface.
What is the velocity of the object
Round answer to 2 significant digits
____ m/s
There's a constant force of 35 N exerted on the object of mass 2.0 kg, so it undergoes an acceleration a of
35 N = (2.0 kg) a → a = 17.5 m/s²
The object travels 8.0 m, so that it attains a velocity v of
v ² = 2 (17.5 m/s²) (8.0 m) → v ≈ 16.73 m/s ≈ 17 m/s
The velocity of the 2 Kg object which travels 8 m along the horizontal frictionless surface is 17 m/s
How to determine the acceleration Force (F) = 35 NMass (m) = 2 KgAcceleration (a) =?a = F / m
a = 35 / 2
a = 17.5 m/s²
How to determine the velocity Initial velocity (u) = 0 m/sDistance (s) = 8 mAcceleration (a) = 17.5 m/s²Final velocity (v) =?v² = u² + 2as
v² = 0² + (2 × 17.5 × 8)
v² = 280
Take the square root of both side
v = √280
v = 17 m/s
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State the lows of reflection
Answer:
The law of reflection states that when a ray of light reflects off a surface, the angle of incidence is equal to the angle of reflection.
Explanation:
Answer: The law of reflection states that when a ray of light reflects off a surface, the angle of incidence is equal to the angle of reflection.
Two objects are shown below. One is neutral and the other is negative. What do you predict would happen?
Answer:
The body becomes a positive charged body.
Explanation:
Given that two objects are shown below. One is neutral and the other is negative. What do you predict would happen?
According to the law of static electricity, like charges repel each other while unlike charges attract each other.
Since one of the object is neutral and the other one is negative, there will neither attraction nor repulsion between them.
Also, according to Electrostatic induction, the neural body can be charged and becomes positive.
The negative body will attract all the positive charges to its side, and repel all the negative charges to the other side. If the body is touched at the other end, the whole negative charges will be earthed and the body will become a positive body.
B. Which of these uses the most power? Explain your answer.
1) 160 J of work in 8 seconds
2) 80 J of work is 4 seconds
3) 180 J of work in 9 seconds
Answer:
p=w/t
160/8=20
80/4=20
180/9=20
...so..all these uses equal power
how would a position-time function look like for linearly increasing negative velocity regions?
Answer:
Hmmm
Explanation:
Here what I know... If a function gives the position of something as a function of time, the first derivative gives its velocity, and the second derivative gives its acceleration. So, you differentiate position to get velocity, and you differentiate velocity to get acceleration. where t is in seconds and H(t) is in inches.
Does this help?
Which of the following determines and objects ability to float in water
Atomic number
Mass and volume
Displacement in a liquid
Mass and gravity
Which type of electromagnetic waves would the best to use in an object designed to cook food?
А. gamma waves
B. visible waves
C. infrared waves
D. microwaves
Answer:
C. infrared waves
Explanation:
Microwaves are the electromagnetic waves which would the best to use in an object designed to cook food. Thus, the correct option is D.
What are Microwaves?Microwave is a form of electromagnetic radiation with the wavelengths ranging from about one meter to about one millimeter which is corresponding to the frequencies in the range between 300 MHz and 300 GHz, respectively.
Microwaves are used for cooking food faster than the conventional ovens and would not make a mess in the process. This reheats food instantly quickly. It is helpful for the health conscious people. Microwaves also ensure that a person will never burn the food again. Microwaves are also very economical and energy efficient.
Therefore, the correct option is D.
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Which lighting source has lower energy costs and a longer life but can be dangerous?
a. fluorescent
b. laser
c. incandescent
d. neon
Answer: I'm like 98% sure it's fluorescent cause it's got mercury
Explanation:
How will recreation be affected by sea level rise?
Answer:
Scientists predict that sea levels could rise up to six-feet by 2100. An increase this large will swallow beaches—impacting public access, beach recreation, and healthy ecosystems. ... With less sand beach-goers will have a completely different recreational experience in the future.
Explanation:
What causes wind to follow patterns
Answer: Wind follows a pattern because the Earth is spinning in one motion. If we were spinning in one way then another we would have one day go by then the spinning cycle would change and we would have to go through that day all over again, it would not be logical because then we would be in the same season as well, we would be in one season for the rest of our lives until we died.
I don't know if this was helpfull or not but I hope it was somewhat close to helpful? If it is not then please do not report this, I am sorry if this was the least bit helpful.
HAVE A NICE DAY! :)
Why is a protective apron or lab coat important to use when working with acids?
Acids conduct electricity and contact could cause a shock.
Acids react with lipids and can cause damage to skin tissue.
Acids break down fabrics and can cause burns if the acids are strong.
Acids have a slippery feel and could result in a fall.
Answer:
Acids break down fabrics and can cause burns if the acids are strong.
Explanation:
A protective apron or lab coat is important when working with acids because acids break down fabrics and can cause burns if the acids are strong.
An acid is a substance that interacts with water to produce excess hydroxonium ions in an aqueous solution. A strong acid ionizes completely in solution. When they come in contact with a fabric, they break them down violently. So, if they come in contact with the skin, it causes a violent break down of body tissues. The apron acts a protective layer.Answer:
C
Explanation:
I got it right
Would a ship in Lake Ontario (fresh water) float higher or lower in the water than in the Atlantic Ocean (salt water)?
Atlantic Ocean (salt water)
how does light travel?
plaza help
Answer:
your answer will be the letter B
define time in short answer
Answer:
measurable period during which an action, process, or condition exists or continues
Explanation:
Answer:
Time is the indefinite continued progress of existence and events that occur in an apparently irreversible succession from the past, through the present, into the future.
Explanation:
hope it helps...
A man standing on top of a 30 m tall building throws a brick downwards with a velocity of 12 m/s. Determine the speed of the brick just before it hits the ground.
Answer:
27.1m/s
Explanation:
Given parameters:
Height of the building = 30m
Initial velocity = 12m/s
Unknown:
Final velocity = ?
Solution:
We apply one of the kinematics equation to solve this problem:
v² = u² + 2gh
v is the final velocity
u is the initial velocity
g is the acceleration due to gravity
h is the height
v² = 12² + (2 x 9.8 x 30)
v = 27.1m/s
Tom drives on a highway and never changes his speed for the whole journey. He drives for 300 miles and it takes him 5 hours. What is Tom's speed on the highway?
Answer:
QESARDFRGTSRTATFREVERSRvrvqwqv
Explanation:
vfqfvcafbraf w rfdsd AEWvd a
Which of the following statements about infrared telescopes is NOT true?
a. They are typically operated at lower temperatures.
b. They are especially helpful for viewing cool or obscured astronomical objects.
c. They were first built in the 1960s.
d. They are often placed on mountaintops.
e. They do not work well at high altitudes.
Answer:
a. They are typically operated at lower temperatures.
a. They are typically operated at lower temperatures.b. They are especially helpful for viewing cool or obscured astronomical objects.
4. A 5.00-kg sled starts at rest and accelerates down a 45.0° incline. The coefficient of
kinetic friction between the mass and the incline is .185.
a) What is the value of the of the acceleration of the sled
Answer: [tex]5.64\ m/s^2[/tex]
Explanation:
Given
mass of sled m=5 kg
Elevation [tex]\theta =45^{\circ}[/tex]
[tex]\mu _k=0.185[/tex] (coefficient of kinetic friction)
Friction will oppose the motion of the sled while sled weight sin component helps it to move down the incline
[tex]W\sin\theta-F_r=ma\\where\\W=weight(mg)\\F_r=Friction(\mu_kmg\cos\theta)\\a=acceleration[/tex]
Substituting values
[tex]mg\sin \theta-\mu_kmgcos\theta=ma\\g\sin \theta-\mu_kg\cos \theta=a\\a=g(\sin 45^{\circ}-0.185\times \cos 45^{\circ})\\a=5.64\ m/s^2[/tex]
An apple in a tree has a mass of 0.21 kg. If it is 7.2 meters above the ground, how much potential energy does it have?
Answer:
14.8J
Explanation:
PE=MGH
M=0.21
G=9.8m/s
H= 7.2 m
0.21x7.2x9.8= 14.8176 J
How much water is displaced by a solid object with a volume of 9 cm3 that is completely submerged in the water?
Given :
An object with a volume of 9 cm³ is completely submerged in the water.
To Find :
How much water is displaced by the object.
Solution :
According to Archimedes' principle, the amount of volume displaced of fluid when an object is fully and partially submerged into that is equal to the volume of the object below the surface of liquid.
Now, it is given that object is fully submerged into water.
Therefore, volume of water displaced by the object is 9 cm³.
A laser beam is directed at the Moon, 380,000 km from the Earth. The beam diverges at an angle of \thetaθ of 0.8 x 10-5 rad. What diameter spot, in m, will it make on the Moon?
Answer:
3040 m
Explanation:
The formula to apply here is ;
d=∅*r where
d is the diameter of the spot , ?
∅ is angle of divergence in radians, = 0.8 * 10⁻⁵rad
r is distance of Moon from Earth, =380,000 km
Applying the formula as;
d=∅*r
d= {0.8 *10⁻⁵} * 380,000 * 1000
d= 3040 m
What is the electric potential at a distance of 1.2 m from a 7.5 UC point charge?
5.6 x 104 v
8.1 x 104 V
5.6 % 1010 V
8.1 x 1010 V
Answer:
5.6x10^4
Explanation:
use the equation V=kq/d
k is the constant 8.99x10^9
V=(8.99x10^9)q/d
q is the charge, 7.5 micro coulombs, but to get coulombs, multiply by 10^-6
V=(8.99x10^9)(7.5x10^-6)/d
And from the problem, we know that the distance is 1.2 meters
V=(8.99x10^9)(7.5x10^-6)/1.2
This simplifies to 5.6x10^4
The electric potential is 5.6 x 10⁴ v.
To find the electric potential the distance = 1.2 m
Charge q = 7.5 UC
What is electric potential and find the value?The amount of work needed to move a unit charge from the known point to some unknown point against the electric field is said to be electric potential.
Formula of an electric potential is
V = k ( q/r) volt
V - electric potential
k - Coulomb constant (8.99x10^9)
q - charge
r- distance of separation
V = (8.99x10⁹) (q/d)
q = 7.5 UC ( micro coulomb) 10⁻⁶ C
V=(8.99x10⁹)(7.5x10⁻⁶)/d
Substituting the values,
V=(8.99x10⁹)(7.5x10⁻⁶)/1.2
V = 5.6x10⁴ v
Thus, option A is correct.
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On the pH scale, where can you find strong acids and strong bases?
Explanation:
The pH scale is an index ranging from 0-14 which measures the acidity or basicity of substances. The closer the pH of an acid to 0 the stronger it is and the closer the pH of a base to 14,the stronger it is.
help!! what are the blanks???
The earth receives energy from the sun in one day than all the energy consumed by humans in one year.
Amount of energy received from the sun
The sun provides around 174 petawatts of energy to Earth, of which 89 petawatts is absorbed by the planet.
The Global energy consumption is roughly 15 terawatts annually.
Thus, we can conclude that, the earth receives energy from the sun in one day than all the energy consumed by humans in one year.
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