We can show that air is dissolved in water with the help of following activity: Take some water in a glass or metal container like pan and heat it. Just before water begins to boil, you will notice some bubbles at the inner surface of the pan. These bubbles come from the air dissolved in water.
Given the hypothesis that the element zinc prevents cancer, which of the following procedures BEST exemplifies the nature of scientific investigation?
A- Analyze zinc, looking for different forms
B- Do research on zinc and its uses throughout history to determine if there is evidence that zinc prevents incidence of cancer
C- Rely on testimony of friends and relatives, as well as conduct a survey to see if there is a concentration of cancer in the people not taking zinc supplements
D- Give zinc supplements to a group of rats and not to another group. After a period of time, determine if there is a higher incidence of cancer in the control group
Answer:D
Explanation: i found the answer in an answer key!
Give zinc supplements to certain rats while withholding them from others. Determine whether the control group's cancer incidence has increased over time. Hence, option D is correct.
What is Scientific Investigation?Scientific investigation refers to the procedures and procedures used by scientists to create hypotheses, carry out experiments, collect and analyze data, and come to conclusions. Sometimes the evidence doesn't offer adequate answers, but it can raise fresh questions that need to be looked into. Scientific methods are employed by scientists primarily to conduct scientific research.
The steps in Scientific Investigation are :
Make some observationsAsk questions on basis of observationsMake a HypothesisCheck that HypothesisExtract ConclusionCommunicate the results.The hypothesis portion is the best way to define a hypothesis as a potential solution to a problem in science. Though it may be falsifiable, it is crucial that the hypothesis be rational. Observations that would contradict the hypothesis must be made if we want to show it to be false. In this case, we'll check to determine if the problem is with just one particular electrical item or with all of them.
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A car is driving at 85 km/h and the driver spots a stop sign ahead. What coefficient of friction is needed to stop the car at the stop sign if the stop sign is 900m away?
Answer:
μ = 0.0315
Explanation:
Since the car moves on a horizontal surface, if we sum forces equal to zero on the Y-axis, we can determine the value of the normal force exerted by the ground on the vehicle. This force is equal to the weight of the cart (product of its mass by gravity)
N = m*g (1)
The friction force is equal to the product of the normal force by the coefficient of friction.
F = μ*N (2)
This way replacing 1 in 2, we have:
F = μ*m*g (2)
Using the theorem of work and energy, which tells us that the sum of the potential and kinetic energies and the work done on a body is equal to the final kinetic energy of the body. We can determine an equation that relates the frictional force to the initial speed of the carriage, so we will determine the coefficient of friction.
[tex]\frac{1}{2} *m*v_{i}^{2}-(F*d)= \frac{1}{2} *m*v_{f}^{2}[/tex]
where:
vf = final velocity = 0
vi = initial velocity = 85 [km/h] = 23.61 [m/s]
d = displacement = 900 [m]
F = friction force [N]
The final velocity is zero since when the vehicle has traveled 900 meters its velocity is zero.
Now replacing:
(1/2)*m*(23.61)^2 = μ*m*g*d
0.5*(23.61)^2 = μ*9,81*900
μ = 0.0315
Question 1: Explain how stars are formed.
In a Young's double-slit experiment the separation distance y between the second-order bright fringe and the central bright fringe on a flat screen is 0.0177 m, when the light has a wavelength of 425 nm. Assume that the angles are small enough so that sin is approximately equal to tan . Find the separation y when the light has a wavelength of 560 nm.
Answer:
y = 0.0233 m
Explanation:
In a Young's Double Slit Experiment the distance between two consecutive bright fringes is given by the formula:
Δx = λL/d
where,
Δx = distance between fringes
λ = wavelength of light
L = Distance between screen and slits
d = Slit Separation
Now, for initial case:
λ = 425 nm = 4.25 x 10⁻⁷ m
y = 2Δx = 0.0177 m => Δx = 8.85 x 10⁻³ m
Therefore,
8.85 x 10⁻³ m = (4.25 x 10⁻⁷ m)L/d
L/d = (8.85 x 10⁻³ m)/(4.25 x 10⁻⁷ m)
L/d = 2.08 x 10⁴
using this for λ = 560 nm = 5.6 x 10⁻⁷ m:
Δx = (5.6 x 10⁻⁷ m)(2.08 x 10⁴)
Δx = 0.0116 m
and,
y = 2Δx
y = (2)(0.0116 m)
y = 0.0233 m
The mass of the basketball shown below is 4 times the mass of the baseball.
Basketball
Baseball
If the two balls are moving at the same speed, and the basketball and the baseball has a kinetic
energy of 10.0 J, what is the kinetic energy of the basketball?
2.5 J
5.03
10.03
20.0 J
Answer:
40.0 Joules. None of the answers is correctExplanation:
Kinetic energy of an object is expressed as;
KE = 1/2mv² where;
m is the mass of the object
V is the velocity of the object.
Let Ma be the mass of the basketball and Mb be the mass of baseball.
If the mass of the basketball shown below is 4 times the mass of the baseball, then Ma = 4Mb
KE of the basket ball = 1/2MaVa²
Va² = 2(KE)a/Ma ...... 1
KE of the baseball = 1/2MbVb²
Vb² = 2(KE)b/Mb .......... 2
Since their velocities are the same, hence Va²= Vb²
2(KE)a/Ma = 2(KE)b/Mb
Substituting Ma = 4Mb into the resulting expression.
2(KE)a/4Mb = 2(KE)b/Mb
2(KE)a/4 = 2(KE)b
Given Kinetic energy of baseball (KE)b = 10.0J, the expression becomes;
2(KE)a/4 = 2(10)
2(KE)a = 4*20
2(KE)a = 80
(KE)a = 80/2
(KE)a = 40.0J
Hence the kinetic energy of the basketball is 40.0Joules
Xiang is comparing the strong nuclear force and the weak nuclear force.
Which describes the weak nuclear force only? Check all that apply.
is attractive
is repulsive
has an infinite range
has a very small range
is stronger than the gravitational force
is weaker than the electromagnetic forc
Answer:
answer is 2 and 6 on edge2020, sorry that its a week late
Explanation:
Answers:
B. is repulsive
F. is weaker than the electromagnetic force
Explanation:
Correct on Edge 2021
A common method to measure thermal conductivity of a biomaterial is to insert a long metallic probe axially into the center of a long cylindrical container of the material. The probe is maintained at some uniform temperature Ti, and the outside of the container is maintained at a temperature To. Inside the metallic probe is an electrical heater for which the electrical power is measured. If the diameter of the probe maintained at 50°C is 1 cm, the outer diameter of the container maintained at 20°C is 4 cm, the length of the cylinder container is 60 cm, and the power input is 40.8 W, calculate the thermal conductivity of this material.
Answer:
The thermal conductivity of the biomaterial is approximately 1.571 watts per meter-Celsius.
Explanation:
Let suppose that thermal conduction is uniform and one-dimensional, the conduction heat transfer ([tex]\dot Q[/tex]), measured in watts, in the hollow cylinder is:
[tex]\dot Q = \frac{2\cdot k\cdot L}{\ln \left(\frac{D_{o}}{D_{i}} \right)}\cdot (T_{i}-T_{o})[/tex]
Where:
[tex]k[/tex] - Thermal conductivity, measured in watts per meter-Celsius.
[tex]L[/tex] - Length of the cylinder, measured in meters.
[tex]D_{i}[/tex] - Inner diameter, measured in meters.
[tex]D_{o}[/tex] - Outer diameter, measured in meters.
[tex]T_{i}[/tex] - Temperature at inner surface, measured in Celsius.
[tex]T_{o}[/tex] - Temperature at outer surface, measured in Celsius.
Now we clear the thermal conductivity in the equation:
[tex]k = \frac{\dot Q}{2\cdot L\cdot (T_{i}-T_{o})}\cdot \ln\left(\frac{D_{o}}{D_{i}} \right)[/tex]
If we know that [tex]\dot Q = 40.8\,W[/tex], [tex]L = 0.6\,m[/tex], [tex]T_{i} = 50\,^{\circ}C[/tex], [tex]T_{o} = 20\,^{\circ}C[/tex], [tex]D_{i} = 0.01\,m[/tex] and [tex]D_{o} = 0.04\,m[/tex], the thermal conductivity of the biomaterial is:
[tex]k = \left[\frac{40.8\,W}{2\cdot (0.6\,m)\cdot (50\,^{\circ}C-20\,^{\circ}C)}\right]\cdot \ln \left(\frac{0.04\,m}{0.01\,m} \right)[/tex]
[tex]k \approx 1.571\,\frac{W}{m\cdot ^{\circ}C}[/tex]
The thermal conductivity of the biomaterial is approximately 1.571 watts per meter-Celsius.
Statement A: Area of a rectangle with measured length = 2.536 mm and width = 1.4 mm.
Statement B: Area of a rectangle with measured length = 2.536 mm and width = 1.41 mm.
Since you are not told specific numbers of significant figures to round to, you must use the rules for multiplying numbers while respecting significant figures. If you need a reminder, consult the hint.
Determine the correct relationship between the statements.
Explanation:
Formula for calculating the area of a rectangle A = Length *width
For statement A;
Given area of a rectangle with measured length = 2.536 mm and width = 1.4 mm.
Area of the rectangle = 2.536mm * 1.4mm
Area of the rectangle = 3.5504mm²
The rule of significant figures states that we should always convert the answer to the least number of significant figure amount the given value in question. Since 1.4mm has 2 significant figure, hence we will convert our answer to 2 significant figure.
Area of the rectangle = 3.6mm² (to 2sf)
For statement B;
Given area of a rectangle with measured length = 2.536 mm and width = 1.41 mm.
Area of the rectangle = 2.536mm * 1.41mm
Area of the rectangle = 3.57576mm²
Similarly, Since 1.41mm has 3 significant figure compare to 2.536 that has 4sf, hence we will convert our answer to 3 significant figure.
Area of the rectangle = 3.58mm² (to 3sf)
Based on the conversion, it can be seen that 3.6mm² is greater than 3.58mm², hence the area of rectangle in statement A is greater than the area of the rectangle in statement B.
an object moves 12m to the right. if its acceleration was 2m/s2 and its final velocity is 25m/s, find it initial velocity.
The sound wave has a frequency of 426 Hz. What is the period? What is the wavelength?
Answer:
See below
Explanation:
Using the speed of sound in air as 343 m/s :
343 = wavelength * frequency
= wavelength * 426
wavelength = .81 meters
Period is just 1/frequency = .00235 seconds
i’ll give brainliest answer to correct one, please help
Answer:
i believe its D because he is not sliding and he is applying force on the wall
Explanation:
hope this helps plz mark brainliest
A.) A bullet accelerates at 8000 m/s2
as it
is fired from a 1.6m rifle. How much
time will it take to clear the barrel?
B.) How much velocity does that rifle
impart on the bullet?
Answer:
0.02 s
160 m/s
Explanation:
Given:
Δx = 1.6 m
v₀ = 0 m/s
a = 8000 m/s²
A) Find t.
Δx = v₀ t + ½ at²
1.6 m = (0 m/s) t + ½ (8000 m/s²) t²
t = 0.02 s
B) Find v.
v² = v₀² + 2aΔx
v² = (0 m/s)² + 2 (8000 m/s²) (1.6 m)
v = 160 m/s
The more threads a screw has the greater the holding power of the screw
true or false
Answer:
true
Explanation:
Answer:true
Explanation:
A person jogs 10 miles, at a speed of 5 mi./h how long did it take ?
Answer:
2 hours!!! 5 miles an hour so 10 miles every two hours.
Answer:
We are given that it takes 1/2 an hour for the trip. This is a time:
t = 1/2
We are given that he averages 34 miles per hour. This is a rate:
r = 34
We are asked how few he has traveled. This is a distance. We use the d=rt equation:
d = rt
= (34)(1/2)
= 17
Markus lives 17 miles from work.
Explanation:
hope this will help you
Elements are organized on the periodic table based on their properties. Which statement correctly predicts and explains the chemical reactivity of two metals?
Rubidium (Rb) is more reactive than strontium (Sr) because strontium atoms must lose more electrons.
Sodium (Na) is more reactive than magnesium (Mg) because sodium atoms must gain more electrons.
Calcium (Ca) is less reactive than potassium (K) because potassium atoms must lose more electrons.
Beryllium (Be) is less reactive than lithium (Li) because beryllium atoms must gain more electrons.
Answer:Rubidium or answer 1
Explanation:took quiz
Answer: Rubidium (Rb) is more reactive than strontium (Sr) because strontium atoms must lose more electrons.
Explanation: Look at the elements they are organized on the periodic table based on their properties. (A) correctly predicts and explains the chemical reactivity of two metals.
Earths gravity acts upon objects with a steady force of
Answer:
9.8 m/s²
Explanation:
Earths gravity acts upon objects with a steady force of 9.8 m/s². The force of gravity is attractive in nature. It acts between two objects. It always acts towards the ground. The force off gravity is given by :
F = W = mg
m is mass of the object and g is the acceleration due to gravity. The value of g is 9.8 m/s². Hence, Earth's gravity acts upon objects with a steady force of 9.8 m/s².
Answer:
the answer is actually D. 9.8 meters per second squared
Explanation:
I took the quiz.. please mark brainliest. Also hope you get it correct;)
The weight of a box is found to be 30 N. What is the approximate mass of the box?
3 kg
300 kg
120 kg
30 kg
Answer:
3kg
Explanation:
3kg is the appropriate mass
Answer:
3kg
Explanation:
just took the test
Which of these would be the BEST way to illustrate the percentage of students receiving A's,
B's, C's, D's and F's on a recent test? *
Bar graph
Circle graph
Line graph
Scatter graph
Answer:
it’s circle graph
Explanation:
the best type of graph to use to show the percentages of a whole is a circle graph
why do we breath air?
Answer:
We breath air for us to supply oxygens in terms of functioning the circulatory system because oxygen can be transported as blood. We breath air because it has many minerals in it.
Explanation:
You are standing on a scale in an elevator that is moving upward with a constant velocity. The scale reads 600 N. The following table shows five options for what the scale reads when the elevator slows down as it comes to a stop, when it is stopped, and when it picks up speed on down. Which one of the five options correctly describes the scale's readings? Note that the symbol < means "less than" and > means "greater than."
Option Elevator slows down Elevator is stopped Elevator picks up speed
as it comes to a half on its way back down
(a) >600 N >600 N >600 N
(b) <600 N 600 N <600 N
c) >600 N 600 N <600 N
(d) <600 N <600 N <600 N
(e) <600 N 600 N >600 N
Answer:
C. >600 N 600 N <600 N
Explanation:
The scale's reading when when the elevator slows down as it comes to a stop, when it is stopped, and when it picks up speed on down is >600 N, 600 N, <600 N respectively.
To understand this we have to first understand weight.
What is weight?Weight is a product of mass and gravitational acceleration.Weight W = mg , where m = mass of an object , g = gravitational acceleration.The gravitational force increases as the height of an object increases.What happens to scale's reading when an elevator changes its position? The scale's reading is 600 N.When an elevator goes upwards and slows down , the Earth's gravity pulls it down so the force will be 600 N + force applied by earth so it will be >600 N.When an elevator stops it is at its natural height so, the force will be 600 N.When an elevator picks up speed on down, the force will be less than 600 N so it will be <600 N.So, the scale's reading is >600 N 600 N <600 N, hence the correct answer is option C.
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In getting ready to slam-dunk the ball, a basketball player starts from rest and sprints to a speed of 5.45 m/s in 3.02 s. Assuming that the player accelerates uniformly, determine the distance he runs.
Recall that average velocity v is given by
v = ∆x/∆t
where ∆x is displacement and ∆t is time.
Under constant acceleration, average velocity is also equal to the average of the initial and final velocities,
v = (v₂ + v₁)/2
The player starts at rest, so v₁ = 0, and speeds up to v₂ = 5.45 m/s in a matter of ∆t = 3.02 s. So
∆x = (v₂ + v₁) ∆t / 2
∆x = (5.45 m/s) * (3.02 s) / 2
∆x ≈ 8.23 m
What happens in a tug of war if the net forces are balanced and why?
Answer:
Balanced forces are responsible for unchanging motion. Balanced forces are forces where the effect of one force is cancelled out by another. A tug of war, where each team is pulling equally on the rope, is an example of balanced forces. The forces exerted on the rope are equal in size and opposite in direction.
Explanation:
You have four identical conducting spheres: A, B, C, and D. In each scenario below, sphere A starts with a charge of -Q, sphere C starts out with a charge of Q, and spheres B and D start out neutral. Then the spheres are touched to each other and separated in the order described. Any spheres not in contact are held very far away. For each scenario, give the final charge of sphere C as a whole number fraction of Q. For example, if you decide that the final charge of sphere C is -Q/7, enter \"-1\" in the numerator and \"7\" in the denominator. Remember! Before each scenario begins, spheres A, B, C, and D are reset to charges of -Q, 0, Q, and 0 again.
Scenario 1: A and B touch and are separated, then A and C touch and are separated, then A and D touch and are separated.
Scenario 2: A and D touch and are separated, then D and C touch and are separated, then D and A touch and are separated, then A and B touch and are separated.
Scenario 3: A and B touch and are separated, then B and D touch and are separated, then C and D touch and are separated.
Answer:
1) Q_c = - ½ Q , 2) Q_c = + ¼ Q , 3) Q_c= 3/8 Q
Explanation:
For this exercise we must use that equal charges repel and charges with different signs attract. When two objects are in contact, the charges are evenly distributed between them.
Scenario 1.
when the two spheres touch the charge -Q is distributed between them, when separating each sphere has a charge = -1/2 Q
as there are no more interacts sphere C its charge is
Q_c = - ½ Q
Scenario 2
when the two spheres touch the charge -Q is distributed between them, when separating each one has a charge
Q_a = Q_d = - ½ Q
now the sphere D and C touch the charge is Q_net = -1/2 Q + Q = + ½ Q
when separating each sphere has half the charge
Q_d = Q_c = + ¼ Q
since sphere C has no more interaction, its charge is
Q_c = + ¼ Q
Scenario 3
A and B touch the net charge is Q_net = - Q + 0 = - Q
when parting
Q_a = Q_b = - ½ Q
now B and D touch, the charge is Q_net = - ½ Q +0 = - ½ Q
when parting
Q_b = Q_d = - ¼ Q
finally C and D touch
the net charge is Q_net = Q- ¼ Q = ¾ Q
when separating each one is left with half the load
Q_c = Q_d = 3/8 Q
Q_c= 3/8 Q
Quadrilateral A has side lengths 3, 4, 5, and 6. Quadrilateral B is a scaled copy of Quadrilateral A with a scale factor of 2. Select all of the following that are side lengths of Quadrilateral B. 5 6 7 8 9
Answer: 6 and 8 would be side lengths because if it has a scale factor of 2 then you multiply the ones on the chart.
Explanation:Go find one
A trough is 8m long and has ends which are isosceles triangles with height 3m and width (across the top) of 3m. The trough has a spout at the top of the tank with height 2m. The tank is full of water. (a) How much work is required to pump all of the water out of the tank? (NOTE that the density of water is rho = 1000 kg/m3 and the acceleration due to gravity is 9.8 m/s2 . (b) Suppose the pump breaks down after 4 × 105 J of work has been done. What is the depth of the remaining water in the tank
Answer:
(a) the work required to pump all of the water out is 1.0584 x 10⁶ J
(b) the depth of the remaining water in the tank is 1.87 m
Explanation:
Given;
length of trough, L = 8m
height of the isosceles triangle, h = 3m
width of the isosceles triangle, w = 3m
length of spout, b = 2m
The center mass of isosceles triangle is given by;
[tex]\frac{1}{3} \ of \ height \ of \ the \ triangle = \frac{1}{3} *3 = 1 \ m[/tex] (this is the height below the top of the trough)
The total height water will be pumped, H = 1m + b
H = 1m + 2m = 3m
Determine the volume of the trough;
Volume of the trough = area of the triangle x length of the trough
Volume of trough = [tex]\frac{1}{2}*3*3*(8) = 36 \ m^3[/tex]
(a) The work done in pumping all of the water out;
The work done in pumping all of the water out = potential energy of water at that height, H;
W = mgH
where;
m is mass of water
m = ρV
m = (1000 kg/m³) x (36 m³)
m = 36,000 kg
The work done = mgH
= 36,000 x 9.8 x 3
= 1.0584 x 10⁶ J
(b) after 4 × 10⁵ J of work has been done, the energy required to pump out the remaining water is given by;
ΔE = 1.0584 x 10⁶ J - 4 × 10⁵ J = 658,400 J
The depth of the remaining water is calculated as
658,400 J = mgh
where;
h is the height of the remaining water
658,400 = (36,000 x 9.8)h
658,400 = 352,800h
h = 658,400 / 352,800
h = 1.87 m
Calculate the average speed of a car which moves 200 km in 10 hours.
Answer:
Average speed = (total distance) / (total time)
Total distance = 100 km + 200 km = 300 km
Total time = 2 hrs (first part) + 1/2 hr (stop) + 4 hrs (second part) = 6.5 hrs
Average speed = 300 / 6.5 = 46.154 km/hr (rounded)
Explanation:
A ball is thrown with velocity 30.m⋅s−1at an angle of 40.º below the horizontal. What is the magnitude of the horizontal component of the velocity? Give your answer to the nearest m⋅s−1 and do not include units with your answer.
Answer:
Explanation:
The horizontal component of the velocity is expresssed as;
Vx = Vcos θ
V is the velocity of the ball
θ is the angle of inclination to the horizontal
Given
V = 30m/s
θ = 40°
Vx = 30cos40°
Vx = 22.98
Hence the magnitude of the horizontal component of the velocity to the nearest m/s is 23
Help ASAP). Describe the Net Force lab and explain what the lab demonstrated? Will Mark Brainliest. Working on it now can someone please help
Answer: The net force acting on an object is the sum of all the force acting on it, and the net force of an object is zero. I f the forces acting on it tend to cancel each other. For example you are sit in a chair, the earth's gravity is pulling you down, but the chair is pushing you up with an equal amount of force.
There is my answer from my notebook .I hope its good :)
A moon orbits a planet every 42 hours with a mean orbital radius of .002819 AU. The mass of the moon is 8.932 x 1022 kg. Using Newton’s modification to Kepler’s 3rd law, calculate the Mass of the Planet in kg.
Answer:
The mass of the planet is [tex]1.9407\times10^{27}\ kg[/tex]
Explanation:
Given that,
Time period = 42 hours = 151200 sec
Orbital radius = 0.002819 AU = 421716397.5 m
Mass of moon [tex]m=8.932\times10^{22}\ kg[/tex]
We need to calculate the mass of the planet
Using Kepler’s third law
[tex]T^2\propto a^3[/tex]
[tex]T^2=\dfrac{4\pi^2}{G(M+m)}\times a^3[/tex]
Where, a = orbital radius
T = time period
G = gravitational constant
M = mass of moon
m = mass of planet
Put the value into the formula
[tex](151200)^2=\dfrac{4\pi^2}{6.673\times10^{-11}(8.932\times10^{22}+m)}\times(421716397.5)^3[/tex]
[tex](8.932\times10^{22}+m)=\dfrac{4\pi^2}{6.673\times10^{-11}}\times\dfrac{(421716397.5)^3}{(151200)^2}[/tex]
[tex](8.932\times10^{22}+m)=1.94087\times10^{27}[/tex]
[tex]m=1.94087\times10^{27}-8.932\times10^{22}[/tex]
[tex]m=1.9407\times10^{27}\ kg[/tex]
Hence, The mass of the planet is [tex]1.9407\times10^{27}\ kg[/tex]
1.The amount of food inside a bowl is an example of what? Mass or weight*
2. How much gravity is pulling down on a dog is an example of the dogs what?
Weight or mass
Answer:
1. Mass
2. Weight
Explanation:
1. All the physical quantities that exist in the universe that have mass, are measurable because they can be measured on instruments such as scales. For this example, the amount of food can be measured on a scale and its mass determined in grams or ounces.
2. When we talk about a mass of a body influenced by gravity we are talking about weight, weight is a force that points in the direction of Earth's gravitational acceleration. That is, weight depends on the gravitation that interacts with the body. For the example we have that the weight of the dog is equal to the product of the mass of the dog by the gravity of the Earth.
