On the day of the summer solstice, at noon, Eratosthenes was aware of a deep well on the Nile close to Aswan where the sun shone all the way to the bottom. Because the sun was not overhead in Alexandria, the length of that shadow was not zero.
We believe that the light rays from the sun that reach us are all traveling in the same direction; they are parallel, as the sun is thought to be extremely far away. No shadow would be formed by a vertical stick at point A, a "moderate" shadow by a stick at point B, and a very long shadow by a stick at point C. A radius of the earth leading to point A is shown on the diagram, and another leading to point B. A little geometry reveals that the angle between those two radii and the difference between the shadow angles are the same. In our example, the shadows indicate that during our journey from Florida to Pennsylvania, we had rotated the earth by about 10 degrees.
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A book had 250 J of potential energy when it is on a shelf that is 4.2 m high. What is the mass of the book?
An air-conditioning unit is fastened to a roof that slopes at an angle of θ = 39 ∘ above the horizontal (Figure 1). Its weight is a force F⃗ on the air conditioner that is directed vertically downward. In order that the unit not crush the roof tiles, the component of the unit’s weight perpendicular to the roof cannot exceed 435 N. (One newton, or 1 N, is the SI unit of force. It is equal to 0.2248 lb.) (a) What is the maximum allowed weight of the unit? (b) If the fasteners fail, the unit slides L = 1.30 m along the roof before it comes to a halt against a ledge. How much work does the weight force do on the unit during its slide if the unit has the weight calculated in part (a)? The work done by a force F⃗ on an object that undergoes a displacement s⃗ is W=F⃗ ⋅s⃗ .
A) the maximum weight of the air-conditioning unit allowed is 557.7 N. and B) the work done by force F on the object that undergoes displacement is 456.75 J.
Given in the question,
The angle of the Slope = 39 Degrees
Max Weight perpendicular of the roof allowed = 435 N
Distance of roof = 1.3 meters
Let us assume the force of the weight of air-conditioning unit be F.
Now as the roof is at the slope of 39 degrees, The weight perpendicular to the roof tile will be the cos component of the force F.
Max perpendicular Weight = F×(cos(Ф)),
Put in the values, we get
F × Cos(39) = 435
F = 435/Cos(39)
F = 435/0.78 [ Value of cos39 = 0.78 ]
F = 557.7 N
a) So, the maximum weight of the air-conditioning unit allowed is 557.7 N.
b) If the unit sides down the roof, the vertical distance traveled by the unit will be the sin component of the length traveled by it along the roof.
Vertical Displacement = (Length Along Roof)× Sin(39)
Force vertically Downward = F = 557.7 N
Using Formula, W= F.s, Put in the value, we get
W = F × (Length Along Roof)× Sin(39)
W = 557.7 × 1.3 × 0.63
W = 456.75 J
So, A) the maximum weight of the air-conditioning unit allowed is 557.7 N. and B) the work done by force F on the object that undergoes displacement is 456.75 J.
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Select the best answer for the question.
4. The legal right given to a creator of a work to profit from it is known as
OA. artistic license.
OB. digital permission.
C. plagiarism.
OD. copyright.
Mark for review (Will be highlighted on the review page)
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1
Answer:
Explanation:
The correct option will be the option (d) that is copyright.
The legal right given to a creator for a work to earn profit from it is known as copyright. That works can be about books, music, painting, sculptures, and films, any database programs, advertisements, new technology, maps etc. if any person doesn’t the follow the protocols of this copyright rule then he/she will be punished. For that he/she might have to pay some money for stealing the creator’s work.
So, the correct option will be the copyright.
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under what conditions do plasma exist .?
The plasma exists in the condition of the excited state of matter.
The atmosphere stops being made of gas at a height of about 80 kilometers above the surface of the Earth. Instead, it is composed of ionized gas, which has a balanced ratio of neutral particles, positive ions, and electrons. The name of this state is plasma.
Despite being referred to as the "fourth state of matter," many astrophysicists believe it to be the "first" state because it was the first to form right after the Big Bang.
Energy is required to remove electrons from atoms in order to create plasma. Different types of energy, such as heat, electricity, or light, are possible (ultraviolet light or intense visible light from a laser). Plasmas combine back into neutral gas due to insufficient sustaining power.
Therefore the plasma state of matter exist in energized form and required energy to continue existing which can be provided by many source and form of energy.
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I don’t get how to answer this question
The frequency of the radiation is 3.27×10⁻¹⁴ Hz.
What is frequency of a wave?The frequency of a wave is the number of complete oscillation made by that wave in one seconds. The S.I unit of frequency is Hertz
To calculate the frequency of the radiation, we use the formula below.
Formula:
f = v/λ.................... Equation 1Where:
f = Frequency of the radiationv = Velocity of the radiationλ = Wavelength of the radiationFrom the question,
Given:
v = 3.00×10⁸ m/sλ = 9.17×10⁻⁷ mSubstitute these values into equation 1
f = 3.00×10⁸/9.17×10⁻⁷f = 3.27×10⁻¹⁴ HzHence, the frequency of the radiation is 3.27×10⁻¹⁴ Hz.
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I drop a ball from rest , it falls for 7 sec. What speed did the ball reach
Answer:
-68.6m/s
Explanation:
after 1 second its velocity is -9.8 m/s. after 2 seconds its velocity is -19.6 m/s. after 3 seconds its velocity is -29.4 m/s.
so 7 multiplied by the velocity for 1 second will give you the answer.
A cannon sends a projectile towards a target a distance 1270 m away. The initial velocity makes an angle 26◦ with the horizontal. The target is hit. The acceleration of gravity is 9.8 m/s^2. How high is the highest point of the trajectory?
(Note the magnitude of the initial velocity is 125.6749804)
The maximum height achieved by the projectile shot at an angle of 26° with the horizontal is 155.79 meters.
What is Projectile Motion?
Projectile motion is a form of motion experienced by an object or particle that is projected near earth's surface and moves along a curved path under the action of gravity only.
Given is a projectile projected towards a target a distance 1270 m away. Initial velocity of the projectile is 125.6 m/s and makes an angle 26° with the horizontal.
The vertical component of the initial velocity →
u[y] = 125.6 sin(26°) = 125.6 x 0.44 = 55.26 m/s.
The horizontal component of the initial velocity →
u[x] = 125.6 cos(26°) = 125.6 x 0.89 = 111.78 m/s
Horizontal distance covered →
h[x] = 1270 m
Time taken to travel the horizontal range →
t = h[x] / u[x]
t = 1270 / 111.78 = 11.36 seconds
The time at which the height is maximum →
t [max] = 11.36/2 = 5.68 s
Using Newton's second law of motion for vertical direction -
S[y] = u[y] t + 1/2 a[y] t²
At t = t [max], the vertical height will be maximum -
S[y] (max) = 55.26 x 5.68 - 1/2 x 9.8 x 5.68 x 5.8 =
S[y] (max) = 313.87 - 158.08
S[y] (max) = 155.79 meters.
Hence, the maximum height achieved by the projectile shot at an angle of 26° with the horizontal is 155.79 meters.
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In science, volume may be measured in
O centimeters
O milliliters
O kilograms
O kilometers
Answer: milliliters
Explanation:
centimeters and kilometers are measurements of length/distance. Kilogram is a measurement of weight, and millimeters is a measure of how much space an object takes up.
The circuit diagram below shows the locations of four switches. Which switch configuration creates a short circuit?
Answer:
A
Explanation:
When switches 1 and 2 are 'on' or 'closed' the circuit becomes a short
HELP ASAP
Referring to the map of the temperature field in the room, what was the largest variation in temperature?
1.) 2 degrees
2.) 4 degrees
3.) 1 degree.
4.) none of the above
The internet in countries like North Korea Saudi Arabia and China is
Answer:
Explanation:
The correct answer will be that the internet in north korea, Saudi Arabia and china is controlled by the government.
As in these countries according to the constitution of these countries there is a very much restriction on the civilians even for the internet usage. So the internet usage is controlled by the government in these countries.
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please help ! it’s not the last one <3
Answer:
I think it's initial vertical velocity but I may be wrong
What is the depth of water in a tank with 300,000 gallons of water at 70F when the pressure gauge at the bottom of the tank reads 23 psig?
The depth of water in the tank is determined as 16.2 m.
What is hydrostatic pressure?Hydrostatic pressure is the pressure exerted by a fluid at equilibrium at any point of time due to the force of gravity.
The hydrostatic pressure of the water column is calculated as follows;
P = ρgh
where;
ρ is density of the waterg is acceleration due to gravityh is vertical height or depth of the waterh = P/ρg
The given parameters;
Pressure of the water, P = 23 psig = 158579 N/m²g is acceleration due to gravity = 9.8 m/s²ρ is density of water = 1000 kg/m³h = (158579) / (1000 x 9.8)
h = 16.2 m
Thus, the depth of water in the tank is determined as 16.2 m.
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A man , standing on the top of Tower , throws vertically a ball , with initial velocity of 15 m/s. Assuming that, the coordinates of the inertial reference is attached to the hand of the man, such that the origin coincides with the center of his hand, a) What is the equation describing the motion of the ball
The equation describing the motion of the ball is determined as 15t + 4.9t².
What is equation of motion?This is the equation that describes the motion of an object is known as equation of motion.
The equation describing the motion of the ball is determined as follows;
y = vt + ¹/₂gt²
where;
y is the vertical height of fallt is the time of motiong is acceleration due to gravity = 9.8 m/s²y = 15t + 4.9t²
Thus, the equation describing the motion of the ball is determined as 15t + 4.9t².
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Which of the following must happen in order for atoms to bond either ionically or covalently with one another?
A The valence shells of all atoms must be filled after the bonding occurs
b The chemical properties of the atoms must be satisfied
c The ions must have different charges
d The resulting compound must follow ionic naming conventions
Which of the following must happen in order for atoms to bond either ionically or covalently with one another?
a: The valence shells of all atoms must be filled after the bonding occurs
In order for atoms to bond either ionically or covalently with one another the valence shells of all atoms must be filled after the bonding occurs.
What is an atom?An atom is defined as the smallest unit of matter which forms an element. Every form of matter whether solid,liquid , gas consists of atoms . Each atom has a nucleus which is composed of protons and neutrons and shells in which the electrons revolve.
The protons are positively charged and neutrons are neutral and hence the nucleus is positively charged. The electrons which revolve around the nucleus are negatively charged and hence the atom as a whole is neutral and stable due to presence of oppositely charged particles.
Atoms of the same element are similar as they have number of sub- atomic particles which on combination do not alter the chemical properties of the substances.
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3. Sami pops a helium balloon at a birthday
party. What will happen to the particles of
helium that were in the balloon? sc.8.P.8.1
A The particles will disappear.
B The particles will move together.
The particles will spread out evenly
within the room.
The particles will stick together and sink
to the floor.
The particles of helium that were in the balloon will spread out evenly within the room.
When Sami pops a helium balloon at a birthday party then the particles of helium will just mix with air. The helium gases lighter dense than the air.
Air consists mostly of nitrogen and oxygen but there are also some traces of carbon dioxide and noble gases in air, and helium is one of those noble gases.
Helium -
It is a chemical element with the symbol of He. Its atomic no. is two. It is used for medicine, scientific research, refrigeration, gas for aircraft aircraft. It is a noble gas.The particles of helium that were in the balloon will spread out evenly within the room.
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Which energy transfer occurs when a cube of ice is placed in a glass of
water?
OA. The nuclear energy in the water molecules is released from the ice
into the liquid water.
B. Thermal energy is transferred from the liquid water to the ice.
C. The chemical energy of the ice is transferred to the liquid water.
D. Gravitational potential energy is transferred from the liquid water
to the ice.
SUBMIT
Answer:
B
Explanation:
The ice begins to melt which requires it absorb heat from the water...the water gets cooler and the ice gets smaller
At a certain temperature, a rod is hung from an aluminium frame. A small gap exists between the rod and the floor. The frame and rod are heated uniformly. Explain whether the rod will ever touch the floor, assuming that the rod is made from (a) aluminium and (b) lead.
Answer:
The aluminum rod will never touch the floor since both the frame and the rod expand at the same rateThe lead rod will touch the floor if both frame and rod are heated long enough since the coefficient of linear expansion of lead is greater than the coefficient of linear expansion of aluminumExplanation:
An elevator moves upward while increasing speed. Which of the following statements comparing the force of the cable on the elevator T and the weight of the elevator W is correct?
Answer:
See below
Explanation:
Downward force = weight = mg where g = accel of gravity 9.81 m/s ^2
the tension force acting UPWARD to cause the elevator to accelerate upward is F = T=m(a+g) where ' a ' is the UPWARD acceleration ...the tension must be equal to
the weight of the object + mass of object* acceleration
A bullet is fired horizontally with an initial velocity of 900 m/s at a target located 150 m from the rifle.
a) How much time is required for the bullet to reach the target?
b) Using the approximate value of g = 10 m/s^2, how far does the bullet fall in this time?
If you could show work, that'd be greatly appreciated :) I know the answers, but I'm not sure how they're worked.
Answer:
S = Vx t = 900 t
t = 150 / 900 = 1/6 sec
If the bullet is fired horizontally it will travel 900 m in .167 sec
H = 1/2 g t^2 = 1/2 * 10 * (1/6)^2 = .139 m distance bullet will fall
Recording a change in which of the following would be an
example of a qualitative observation?
a velocity
b color
c force
d power
Chec
The color change would be an example of qualitative observation.
What is qualitative observation?The approach of conducting research known as qualitative observation uses subjective methodologies to collect information or data. Although qualitative observation takes a lot longer than quantitative observation because the goal is to compare quality differences, the research is vast and much more individualized.
The five main senses—sight, smell, touch, taste, and hearing—and how they function are the topics of qualitative observation. This involves attributes rather than measures or numbers.
Hence, recording a color change would be an example of a qualitative observation.
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Which term applies to what happens to visible light when it interacts with transparent glass?
The term is scattering of lights when visible light interacts with transparent glass.
Light interacts with glass atoms when it strikes any surface, even transparent ones, causing it to change direction repeatedly. This process is known as the scattering of light. While some light is reflected throughout the process, the majority of light passes through the glass.
The shorter the wavelength and the higher the frequency, the stronger the scattering due to the wave shape of the lines and their intersections with the particles. The more wavy lines you have, the more likely they are to intersect with a particle. On the other hand, the longer the wave, the lower the frequency, the straighter it is, and the less likely it is to hit the particle.
The curvature of color light is visible during the day because of the refraction of light and total internal reflection. Waves of sunlight produce different colors in different directions. The Rayleigh scattering theory is based on the red color of the sun in the morning and the blue color of the sky.
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A person has a reasonable chance of surviving an automobile crash if the deceleration is no more than 30 "g's."Calculate the magnitude of the force on a 89-kg person accelerating at this rate.
The magnitude of the force on the 89 kg person who is decelerating at 30 m / s² is 272.44 N
According to Newton's second law of motion,
F = m a
m = W / g
F = Force
m = Mass
a = Acceleration
W = Weight
g = acceleration due to gravity
a = 30 m / s²
W = 89 kg
F = 89 * 30 / 9.8
F = 272.44 N
According to Newton's second law of motion, Acceleration of an object is dependent upon the mass of the object and the net force acting on it.
Therefore, the magnitude of the force on the 89 kg person who is decelerating at 30 m / s² is 272.44 N
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Cliff divers at Acapulco jump into the sea from a
cliff 30.1 m high. At the level of the sea, a rock
sticks out a horizontal distance of 13,06 m. The
acceleration of gravity is 9.8m/s². With what
minimum horizontal velocity must the cliff divers
leave the top of the cliff if they are to miss the
rock?
Theacceleration of gravity is 9.8m/s² so velocity = 5.269.
The rate at which an object's position changes when observed from a specific point of view and when measured against a specific unit of time is known as its velocity.
A body or item will have a pressure equivalent to atmospheric pressure when the external pressure pressing on it ceases to exist. In this instance, point A is under some pressure from the liquid. The pressure at point A becomes equal to atmospheric pressure when we tilt the container.
Given, h= 30.1 m
x = 13.06 m
g = 9.8
h = 1/2 gt^2
x = v √(2h)/g
13.06 = v √(2)(30.1)/9.8
13.06 = v (2.47847879613)
13.06 / 2.47847879613 = v
v = 5.269.
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Do you think that something can freeze when it is hot? Why or why not?
Answer:
yes
Explanation:
because if you put a hot object in a cold place the energy from the hot object transfers to the cold air around it and will eventually get such a low temperature that it freezes.
It takes less effort to lift a piano with a pulley. If the piano is lifted 3 meters, then...
It takes less effort to lift a piano with a pulley. If the piano is lifted 3 meters, then the distance traveled by the load is 3 m.
What is output force?Output force is the force exerted on an object by a simple machine.
If the output force is greater than the input force, the mechanical advantage is greater than 1.
The mechanical advantage ratio is output force divided by input force. The larger the mechanical advantage, the easier it is to do work.
Mathematically, the output force of a simple machine is given as;
output force = load x distance moved by load
Thus, it takes less effort to lift a piano with a pulley. If the piano is lifted 3 meters, then the distance traveled by the load is 3 m.
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Which technique is used to check the meaning of certain nonverbal behaviors of the
speaker?
1) reflecting
O2) questioning
3) validating
4) looking away
Answer:
2
Explanation:
answer to the question is written up
The technique that is used to check the meaning of certain nonverbal behaviors of the speaker is looking away. The correct option is 4.
What is nonverbal behavior?Nonverbal communication refers to the transmission of messages or signals via nonverbal platforms such as eye contact, facial expressions, gestures, posture, and body language.
It entails using social cues, kinesics, distance and physical environments/appearance, voice, and touch.
Nonverbal communication methods include your posture, facial expressions, and eye contact. We all use these cues in everyday conversation, even if unconsciously.
When people are thinking, hesitating, or speaking in a non-fluent manner, they tend to look away.
This behavior most likely serves two purposes. The first is to psychologically protect themselves from the embarrassment of being judged for not proceeding.
Thus, the correct option is 4.
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Michael Jordan had the longest hang time record of all NBA players. It was because he:
A- was lighter in weight
B- threw the ball with higher precision
C- did not jump till he was below the hoop
D- jumped up with a faster speed
is mass a physical property of matter
Answer:
yes
Explanation:
Rannie travelled by train from New York to New Jersey She travels 350 kilometers to the north. But, then the track turns back to south 125 kilometers. Calculate Radha's total displacement using displacement formula?
Answer:
225 km north
Explanation:
Displacement = 350 km north + 125 km south
= 350 km north - 125 km north
= 225 km north