Answer:
Water is more dense than air. When water goes through a denser thing, the light is "bent" more towards the "normal" which is a straight, vertical line.
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4. Marcia consumes 8.4 X 10.J (2000 food calories) of energy per day while maintaining a constant weight.
What is the average power she produces in a day? 97 Watts
Answer:
8.40 is your answer.
Explanation:
The average power she produces in a day be 97.22 Watts.
What is power?The quantity of energy moved or converted per unit of time is known as power in physics. The watt, or one joule per second, is the unit of power in the International System of Units. Power is also referred to as activity in ancient writings. A scalar quantity is power.
Marcia consumes total amount of energy per day = 2000 calories = 8.4 × 10⁶ joule.
1 day = 24 × 60 × 60 second = 86400 second
So, average power she produces in a day = energy/time
= 8.4 × 10⁶ joule/86400 second
= 97.22 Watts
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A young diver is practicing his skills before an important team competition. Use the diagram below in order to analyze the energies of the diver and complete the statements below.
Where m = mass (kg), g = 9.8 m/s2, v = velocity (m/s), h = height (m), KE = kinetic energy (J), and GPE = gravitational potential energy (J).
Use the equations above to answer the following questions.
A diver with a mass of 90 kg is at a height of 10 m, and he has not jumped off of the board yet (v = 0 m/s). When the diver reaches a height of 5 m (Point C), his gravitational potential energy is
A. 1350 J
B. 8820 J
C. 4410 J
D. 0 J
and his velocity is
E. 4.5 m/s
F. 0 m/s
G. 3.2 m/s
H. 9.9 m/s
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[tex]\\ \sf\longmapsto GPE=mgh[/tex]
[tex]\\ \sf\longmapsto GPE=90(5)(9.8)[/tex]
[tex]\\ \sf\longmapsto G PE=4410J[/tex]
Now
It's converted to kinetic energy while reaching ground.
[tex]\\ \sf\longmapsto K.E=4410[/tex]
[tex]\\ \sf\longmapsto \dfrac{1}{2}mv^2=4410[/tex]
[tex]\\ \sf\longmapsto 90v^2=8820[/tex]
[tex]\\ \sf\longmapsto v^2=98[/tex]
[tex]\\ \sf\longmapsto v=9.9m/s[/tex]
Done
Answer:
Hope it will help you a lot.
3. Suppose Earth orbited a star whose mass was double the mass of the sun. If the radius of Earth's orbit remained
the same as it is now, then compared with gravitational force between Earth and the sun, the gravitational force
between Earth and the star would be -
A. half as much
B. the same
C. two times as much
D. four times as much
Answer:
F1 = G M m / R^2 current force on earth
F2 = G M * 2 m / R^2 force if mass were doubled
F2 / F1 = 2 the force would be twice as large
The gravitational force between two objects not only depends on the mass but also the distance between them. If the distance to the star is same as to sun, then by doubling mass force also doubles. Thus option C is correct.
What is universal law of gravitation?Gravitational force is the attractive force by which an object attracts other objects into its centre of mass. We are all standing in the ground because of the gravitational pull by earth.
The gravitational force between two objects of mass M1 and M2 at a distance r is written as follows:
g = G M1 M2/ r ² . where, G is gravitational constant.
As per this relation, gravitational force is directly proportional to the mass and inversely proportional to the square of the distance.
If the star has a distance from earth equal to the distance between sun and earth, but its mass is double the mass of sun, then the gravitational force will be two times compared with the sun.
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Help needed for science homework
Which of the following is a completely elastic collision?
A. a ball rebounds against a wall, reversing its direction, but at only half the speed.
B. Two balls collide, stick to each other, and move together after the collision.
C. Two balls collide and move at a right angle to each other after the collision at a reduced speed.
D. Two balls collide head on, each reversing its direction and traveling at half the speed.
E. A ball with velocity v collides with a ball at rest; after the collision the first ball is at rest and the second ball has velocity v.
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Hi there!
Answer E.
For a collision to be completely elastic, there must be NO LOSS in kinetic energy.
We can go through each answer choice:
A. Since the ball rebounds at half the initial speed, there is a loss in kinetic energy. This is NOT an elastic collision.
B. A collision involving sticking is an example of a perfectly INELASTIC collision. This is NOT an elastic collision.
C. A reduced speed indicates that there is a loss of kinetic energy. This is NOT elastic.
D. The balls traveling at half the speed after the collision indicates a loss of kinetic energy, making this collision NOT elastic.
E. This collision indicates an exchange of velocities, characteristic of an elastic collision. We can prove this:
Let:
m = mass of each ball
v = velocity
We have the initial kinetic energy as:
[tex]KE = \frac{1}{2}mv^2 + 0 = \frac{1}{2}mv^2[/tex]
And the final as:
[tex]KE = 0 + \frac{1}{2}mv^2 = \frac{1}{2}mv^2[/tex]
Thus, Kinetic energy is CONSERVED. This collision is ELASTIC.
How much energy is needed just to boil 5kg of water at 100◦ C?
A firecracker is placed in the middle of a room. When the firecracker explodes the parts of the firecracker scatter in all different directions. The total combined momentum of all the parts of the firecracker added together after the explosion must be
A.
more than before the explosion.
B.
less than before the explosion.
C.
can not tell from the given information
D.
the same as before the explosion.
Because momentum is a vector quantity, the total combined momentum of all the parts of the firecracker added together after the explosion must be the same as before the explosion. The correct answer is D
Given that a firecracker is placed in the middle of a room. This means that the firecracker is at rest. That is its momentum is equal to zero. When the firecracker is lit up, it will move in a certain velocity before it explodes. Since the total combined momentum of all the parts of the firecracker scatter in all different directions are considered, that is added up, then momentum will always be conserved. That is,
The momentum of an object before explosion will always be equal to the momentum of the object after explosion.
Because momentum is a vector quantity, in which we must consider it magnitude and direction, the best answer to this question is option D.
That is,
The total combined momentum of all the parts of the firecracker added together after the explosion must be the same as before the explosion
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pls help it's due today
Answer:
Breh seriously. Ugh fine.
1.B
2.D
3.C
4.C
5.D,A and B
6.A,C and D
Alistar places a 6.4 kg block on an incline plane that is 23 degrees above the horizontal. The block starts from rest, and in 2.2 seconds, travels 1.4 meters. What is the force of friction on the block?
fh= 6.4×23
fh=147.2
fv=2.2×1.4
fv=3.08
f=147.2+3.08
f=150.28
The force of friction on the block is 20.798 N.
What is acceleration?Acceleration is the rate at which speed and direction of velocity vary over time. Even if the speed is constant, motion on a circle accelerates because the direction is always shifting.
Due to having both direction and magnitude, it is a vector quantity. Si unit of acceleration is meter/second² (m/s²).
Given parameters:
Mass of the block: m = 6.4 kg.
Angle of inclination = 23°
Hence, Magnitude force acting along the motion = mg sin23°
= 6.4 × 9.8 × sin23° N
= 24.51 N.
The block travels 1.4 meters in 2.2 seconds. Acceleration = (2×1.4)/2.2² m/s²
= 0.58 m/s²
Hence, the force of friction on the block is = F - ma
= 24.51 N - 6.4×0.58 N
= 20.798 N
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A car weighing 8000N is traveling at 45 m/s on a perfectly flat, frictionless road. If the driver slams on the brakes, how far will thw car slide before it comes to a stop?
Without friction, the car cannot stop...
The Sun has a mass of 1.99 x 10^30kg [^30 is an exponent] and is 1.5 x 10^11m [^11 is an exponent] from the earth. The planet Earth is 5.98 x 10^24kg [^24 is an exponent]. What is the gravitational attraction between the sun and the earth? G=6.67×10^-11 (-11 is an exponent)
Answer:
F = G M m / R^2 = 6.67E-11 * 1.99E30 * 5.98E24 / (1.5E11)^2
F = 6.67 * 1.99 * 5.98 / 2.25 E21 Newtons
F = 3.53E22 N
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The equation below shows how to calculate work done by an applied force. W equals the work done in joules (J), F equals the applied force in newtons (N), and d equals the distance in meters (m) over which the force is applied.
W = F × d
This equation can be arranged to calculate the applied force instead:
F = W ÷ d
A scientist was performing some experiments to test the designs of some simple machines. One of her experiments involved a pulley. During the experiment, a total of 2,000 J of work was done to lift a crate 5 m straight up off the floor.
Ignoring the effects of friction, determine the applied force needed to lift the crate.
A.
2,005 N
B.
400 N
C.
10,000 N
D.
1,995 N
Answer:
The solutions to this exercise is B. 400N
A vertical spring stretches 9.6 cm when a 1.3 kg block is hung from its end. (a) Calculate the spring constant. This block is then displaced an additional 5.0 cm downward and released from rest. Find the (b) period, (c) freque
Answer:
F = - K x
a) K = 1.3 kg * 9.8 m/s^2 / .096 m = 133 kg/sec^2
b) ω = (K/m)^1/2 angular frequency of SHM
ω = (133 / 1.3)^1/2 = 10.1 / sec
f = 2 π ω = 6.28 * 10.1 / sec = 63.5 / sec
P = 1/f = .0157 sec
Is mechanical energy the result of both kinetic and potential energy?
Answer:
Yes
Explanation:
Because putting them together would make a type of energy making the answer yes
Fill in the blanks about Newton’s First Law of Motion:
Objects want to ____________ ____________ doing what they’re ____________ ____________ because they are “lazy.” This is called ____________.
Objects want to continue doing what they’re doing because they are “lazy.” This is called law of inertia.
Newton's first law of motion states that an object at rest or uniform motion in a straight line will continue in that state unless it is being acted upon by an external force. This law is also called the law of inertia because it depends on mass.
From the given question, we can fill gaps as follows;
Objects want to continue doing what they’re doing because they are “lazy.” This is called law of inertia.
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A father places his daughter in a swing that is 0.60\,\text{m}0.60m0, point, 60, start text, m, end text above ground. Then he raises the swing to a height of 1.3\,\text{m}1.3m1, point, 3, start text, m, end text and lets go. The girl and the swing have a combined mass of 14\,\text{kg}14kg14, start text, k, g, end text. Assume friction is negligible and use g = 9.8\,\text{m/s}^2g=9.8m/s
2
g, equals, 9, point, 8, start text, m, slash, s, end text, squared.
Calculate the girl’s fastest speed.
This question involves the concepts of the law of conservation of energy and kinetic energy.
The girl's fastest speed is "3.7 m/s".
According to the law of conservation of energy, the girl will have the fastest speed at mean position, which will be calculated as follows:
Loss in Potential Energy = Gain in Kinetic Energy
[tex]mg\Delta h=\frac{1}{2}mv^2\\\\v=\sqrt{2g\Delta h}[/tex]
where,
v = maximum speed = ?
g = acceleration due to gravity = 9.81 m/s²
Δh = change in height = 1.3 m - 0.6 m = 0.7 m
Therefore,
[tex]v=\sqrt{2(9.81\ m/s^2)(0.7\ m)}[/tex]
v = 3.7 m/s
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A machine does 2500 J of work in 1 min. What is the power developed by the machine?
Answer:
41.7 watts
Explanation:
power=work done/time
2500/60seconds
=41.6666
An object is dropped from a 42 m tall building. How long does it take to reach the ground?
Answer:
2.1 seconds
Explanation:
let D represent the height in meters
let g represent gravity in meters per second squared
let t represent time in seconds
D= -42 meters (negative because it falls down)
g= -9.8m/s^2
t= [tex]\frac{-42 meters}{9.8 m/s^2}[/tex]
this gives t= 4.2857 s^2
the meter units cancel out in the division
now we must simplify the units to singular seconds so...
[tex]\sqrt{4.3 s^{2} }[/tex] which simplifies to [tex]\sqrt{4.3}[/tex] x [tex]\sqrt{s^{2} }[/tex]
this equals 2.1 seconds
A car starts with a velocity of 16 m/s and slows at a constant rate of -2m/s2, what is its velocity after 3 s?
After 3 seconds, the car slows down to
16 m/s + (-2 m/s²) (3 s) = 16 m/s - 6 m/s = 10 m/s
12. A lathe mounted on wooden skids is to be slid down a pair of planks placed against the back of a truck.
(a) If the coefficient of friction is 0.28, what angle should the planks make with the ground in order for the lathe to slide down at constant velocity?
(b) When the planks are at this angle, will the lathe start to slide down of its own accord?
(a) The angle the planks make with the ground in order for the lathe to slide down at constant velocity is 90⁰.
(b) Yes, at this angle the lathe will start sliding at constant velocity because of the sharp steepness.
The given parameters:
coefficient of friction, μ = 0.28The net force on the wooden skids is calculated as follows;
[tex]\Sigma F = 0\\\\F - \mu mg cos\theta = 0\\\\ma - \mu mg cos\theta = 0\\\\ma = \mu mg cos \theta \\\\a = \mu g cos\theta\\\\at \ constant \ velocity , \ a = 0\\\\0 = \mu g cos \theta\\\\cos \theta = 0\\\\\theta = 90 ^0[/tex]
Yes, at this angle the lathe will start sliding at constant velocity because of the sharp steepness.
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sue and betti both ski straight down a hill, both starting from rest. sue weighs more than betti. neglecting friction and wind resistance, which skier will be moving the fastest at the bottom of the hill?
Answer:
They are both moving at the same speed since they will have the same acceleration
F = M a describes acceleration
M a = M g sin theta where theta is the slope
One can easily see that
a = g sin theta and the weight does not enter into the equation
What process primes a molecule to change in a way that increases its activity, produces motion, or does work
Answer:
cellular respiration.
explanation: cellular respiration, the process by which organisms combine oxygen with foodstuff molecules, diverting the chemical energy in these substances into life-sustaining activities and discarding, as waste products, carbon dioxide and water.
1 kg ball has eight joules of kinetic energy. what is its speed?
[tex]\\ \sf\Rrightarrow KE=\dfrac{1}{2}mv^2[/tex]
[tex]\\ \sf\Rrightarrow 8=\dfrac{1}{2}v^2[/tex]
[tex]\\ \sf\Rrightarrow v^2=16[/tex]
[tex]\\ \sf\Rrightarrow v=√16[/tex]
[tex]\\ \sf\Rrightarrow v=4m/s[/tex]
Answer:
the answer is 4m/s
What is the distance traveled by the elevator between 8 s and 24 s?
m
The distance is equal to 6 m traveled by elevator between 8 s and 24 s.
What are distance and displacement?The distance is described as the total length covered by an object. Distance is a scalar parameter with no direction. The distance covered by an object is always +ve, it can never be zero.
The displacement is described as the shortest length between two points by the object. The displacement is a vector parameter with direction & magnitude. The displacement can be +ve, -ve, or zero and can increase or decrease over time.
Given the position of the elevator at time t = 8 s at d = 9 m
The position of the elevator at time t = 24 s at d = 15 m
The distance covered by the elevator = 15 - (9) = 15 - 9 = 6 m
Therefore, the distance traveled by an elevator between 8 s and 24 s is equal to 6 m.
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The weight of a person in an elevator at rest = 500 N. Acceleration due to gravity is 9.8 m/s2. When lift accelerated, the tension force is 750 N. What is the acceleration of lift.
Answer:If the elevator accelerated downward then the tension force smallest then 500 N. Otherwise, if the elevator accelerated upward then the tension force larger then 500 N.
The tension force = 750 N because the elevator accelerated upward. Force acts upward has plus sign and force acts downward has minus sign.
T – w = m a
750 – 500 = 50 a
250 = 50 a
a = 250 / 50
a = 5.0 m s–2
Explanation:
Please answer all questions if you do I mark you
Explanation:
1. A
2. B
3. I don't know this one but my guess is b
Why do magnets move objects in different ways?
Answer:
Magnets have two poles, called north and south. The like poles are attracted to unlike poles, but like poles repel each other. For example, the north pole of one magnet is attracted to the south pole of another. ... To make objects move with a magnet attach a piece of metal, or another magnet, to it.
the graph is tied to the reading
here is the reading for the question
students in a physics class observing the race note that each runner maintains the same acceleration from the start ofthe 8.0 second interval until they each reach the finish line where each of the runners slows to a stop. Two students inthe class make the following claims about the runners’ accelerations from the start of the 8.0 second interval until bothrunners are at rest.
Student 1:“Runner A has a positive acceleration until reaching the finish line and then a negative acceleration aftercrossing the finish line in order to “undo” all of the positive velocity she gained. Since Runner B neverhad any positive acceleration, she doesn’t need any negative acceleration to slow to a stop; heracceleration will be zero the whole time.”
Student 2:“But negative values mean away south in this case – how could runner A be turning around? I think bothrunners must have positive accelerations the whole time since they are always moving north.”
For part (c), do not simple repeat the students’ arguments in your answers.
here are the questions:
i.Which aspects of student 1’s reasoning, if any, are correct? Explain your answer.
ii.Which aspects of student 1’s reasoning, if any, are incorrect? Explain your answer.
iii.Which aspects of student 2’s reasoning, if any, are correct? Explain your answer.
iv.Which aspects of student 2’s reasoning, if any, are incorrect? Explain your answer
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the federal government sets upper limits for exposure to electromagnetic energy from _____ known as the sar.
The federal government sets upper limits for exposure to electromagnetic energy from telephones known as the SAR.
Solve the science problem
Answer:
1.hydrogen
2.helium
3. lithium
4.beryllium
5.boron
6.carbon
7.nitrogen
8.oxygen
9.fluorine
10.neon
