which force causes an object to free fall
a) wind
b) fluid forces
c) friction
d) gravity
if a plane was flying at a speed of 400 km/ hr and 2 min later has slowed to 100 km/hr to land what is the acceleration
How could a person easily tell which envelope contained four sheets of paper and which contained five sheets without opening the envelopes what assumption did you make in arriving at your answers
You could tell the difference between two envelopes containing 4 and 5 sheets of paper by comparing their weights. An envelope with 5 sheets should feel heavier than the one with 4 sheets, assuming that all materials involved are identical.
Explanation:One way to tell the difference between two envelopes containing 4 and 5 sheets of paper without opening them would be to use weight as a distinguishing factor. Given that the weight of paper is constant, one sheet of paper would add a perceivable amount of weight to an envelope. Therefore, the envelope with 5 sheets should be heavier than the envelope containing 4 sheets. The assumption here is that both the envelopes and the sheets of paper are identical in every other aspect including size, material, weight, etc.
In theory, if you were to hold each envelope in either hand, the difference in weight should be detectable. It's a common practice in mailrooms where workers are adept at figuring out the number of papers inside envelopes just by weight comparison. This method, however, requires a certain level of sensitivity and practice. The real application of this method can vary based on multiple factors such as individual's sensitivity to weight change, uniformity in the weight of the paper etc.
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All charged objects create an electric field around them. What two factors determine the strength of two electric fields upon the charged objects creating them?
A.) how charge the object creating the field is and the mass of the two charged objects
B.) how charged object creating the field is and the distance between the two charged objects
C.) how charged object creating the field is and whether the objects are positively or negatively charged
D.) how charged object creating the field is in the density of the two charged objects
what two properties show that a drink is a fluid
Answer:
Two properties that show that the drink is a fluid/liquid include its retention of volume and its conformation to the shape of its container.
Explanation:
A star is born when gas and dust from a nebula become so dense and hot that nuclear fusion starts. Which of the following forces is responsible for the formation of a star?
A.
friction
B.
gravitation
C.
magnetism
D.
electromagnetic energy
Answer: B. gravitation
Explanation:
Nebula is a stellar nursery. It is composed of dust and gases. This molecular cloud condenses under its own weight and forms a core which spins and gathers more mass due to gravity. This causes temperature and pressure to rise which kicks in the nuclear fusion reaction and a star is said to be born.
Thus, gravitation is responsible for formation of star.
a swimmer can swim in still water at a speed of 9.50 m/s. he intends to swim directly across the river that has a downstream current of 3.75 m/s. what is his velocity relative to the bank?
The relative velocity of swimmer to the bank is [tex]\boxed{10.21\text{ m/s}}[/tex] and [tex]\boxed{21.54^\circ}[/tex] downstream.
Further Explanation:
The swimmer swims across the river from one end to the other. The river is flowing downstream.
The swimmer will cross the river with some relative velocity.
Given:
The velocity of swimmer is [tex]9.50\text{ m/s}[/tex].
The velocity of river is [tex]3.75\text{ m/s}[/tex] downstream.
Concept:
Consider the direction of velocity of swimmer in positive x-direction.
The velocity of swimmer in vector form:
[tex]V_s=9.50\hat i[/tex]
Consider the direction of downstream current of river in negative y-direction.
The velocity of downstream current in vector form:
[tex]V_r=- 3.75\hat j[/tex]
The relative velocity of swimmer to the bank is the resultant of two vectors in x and y direction.
Magnitude of relative velocity:
[tex]{V_{sr}}=\sqrt{V_r^2+V_s^2}[/tex]
Substitute [tex]9.50\text{ m/s}[/tex] for [tex]V_s[/tex] and [tex]3.75\text{ m/s}[/tex] for [tex]V_r[/tex] in above equation.
[tex]\begin{aligned}{V_{sr}}&=\sqrt{3.75^2+9.50^2}\text{ m/s}\\&=10.21\text{ m/s}\end{aligned}[/tex]
The magnitude of relative velocity of swimmer is [tex]10.21\text{ m/s}[/tex] .
The direction of relative velocity:
[tex]\theta={\tan^{-1}}\left({\dfrac{{{V_r}}}{{{V_s}}}}\right)[/tex]
Substitute [tex]9.50\text{ m/s}[/tex] for [tex]V_s[/tex] and [tex]-3.75\text{ m/s}[/tex] for [tex]V_r[/tex] in above equation.
[tex]\begin{aligned}\theta&={\tan^{-1}}\left({\dfrac{{{-3.75}}}{{{9.50}}}}\right)\\&=21.54^\circ\end{aligned}[/tex]
The direction of relative velocity is [tex]21.54^\circ[/tex] downstream.
Thus, the relative velocity of swimmer to the bank is [tex]\boxed{10.21\text{ m/s}}[/tex] and [tex]\boxed{21.54^\circ}[/tex] downstream.
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Answer Details:
Grade: Middle School
Subject: Physics
Chapter: Scalars and vectors
Keywords:
Swimmer, still, water, speed, 9.50 m/s, intends, directly, river, downstream, current, 3.75 m/s, velocity, relative, bank, vector, direction, 21.5degree and 10.21 m/s.
A student performs a lab measuring the velocities of toy cars of different masses
Answer:
Car 1 and Car 2
Explanation:
5 2.2 11
5.5 2 11
6 1.35 8.1
6.5 1.9 12.35
7 1.35 9.45
What does the phrase rise over run refer to when defining slope
Calculate the density if the mass of a solid material is measured as 15.00 grams and its volume is measured as 5.0 cm3? round off your answer to the proper number of significant figures
Answer:
3.0 gm/cm³
Explanation:
Given,
Mass of solid material (m) = 15.00 grams
volume of the material (v) = 5.0 cm³
We know that density is
[tex]= \frac{mass}{volume}[/tex]
Thus the density of the material is
[tex]= \frac{m}{v}[/tex]
[tex]= \frac{15.00}{5.0}[/tex]
[tex]= 3.0[/tex]
Thus the density is 3.0 gm/cm³.
Suppose a car is traveling at +25.0 m/s, and the driver sees a traffic light turn red. After 0.340 s has elapsed (the reaction time), the driver applies the brakes, and the car decelerates at 7.00 m/s2.
Chalk is an ionic compound. Which is a property of all ionic compounds that makes chalk particularly useful for writing on a chalkboard?
Answer:
Hardness and brittleness
Explanation:
Ionic substances form crystal lattices which allow the compounds to be hard because of the strong attractions between positive and negative ions in the lattice. When pressure is applied to the compound like chalk , it may force ions of the same charge together ( i.e. positive to positive). This is called electrostatic repulsion which is able to break the crystal lattice allowing one to write on the chalkboard.
Why might the 1990 earthquake and volcanic eruption in Luzon be related?
A) Both earthquakes and volcanic eruptions are caused by plate tectonics and can
occur in patterns.
B)Earthquakes occur in San Francisco but not in Chicago.
C) Tectonic plates can form deep ocean trenches, such as the Mariana Trench in the Pacific Ocean.
D) On April 2, Mount Pinatubo sent an explosion of steam, water, ash, and rock into the air.
Answer:
Answer: C
Explanation:
Study the following ocean currents map.
Which statement is most likely correct about the average temperatures in San Diego, California as compared to Savannah, Georgia?
It is higher in Savannah because of the cool ocean currents from the south.
It is higher in Savannah because of the warm ocean currents from the north.
It is lower in San Diego because of the warm ocean currents from the south.
It is lower in San Diego because of the cool ocean currents from the north.
The statement is most likely correct about the average temperatures in San Diego, California as compared to Savannah, Georgia is;
Option D: It is lower in San Diego because of the cool ocean currents from the north.
From the map, we see two locations namely;
San diego and Savannah.
Now, upon careful observations of the current direction at San Diego , we see that the current is moving from the north towards the equator and as such we till term it as cool ocean currents.
However, in Savannah, the direction of the currents is away from the equator and as such we will call it warm currents.
In conclusion, since cool currents are coming to San Diego, it will have a lower temperature than at Savannah.
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The mixture use separated was a mixture of iron feelings sand and salt based on your understanding of matter is this mixture a homogenous or mixture or heterogenous mixture
Help please
Any unit of distance divided by any unit of time creates a unit of _____.
A. speed
B. velocity
C. position
D. acceleration
Can protons be gained or lost in an element?
The Greek philosopher Democritus coined what word for a tiny piece of matter that cannot be divided?
A - Element
B - Atom
C - Electron
D - Molecule
Why is it that auroral displays above Colorado can be forecast several days in advance?
What are some tools that are used for tornadoes
Describe a situation in which the displacement f a roller skater is 0 km, but the distance traveled is 2 km.
predict which will fall to the ground faster a crumpled paper or flat sheet of paper
How is our planets giant,thermohaline system of warm and cold water like a massive convection current
As you know, the oceans are a complex system that covers most of the earth, and contains a huge amount of resources. Protecting these resources is one reason to try and prevent the pollution of the oceans.
Algae is one ocean resource in particular that is vulnerable to pollution. The algae are a valuable resource because they absorb carbon dioxide from the atmosphere and release ____________ into the atmosphere.
A) oxygen
B) nitrogen
C) water vapor
D) carbon monoxide
Algae are green in color because they have chlorophyll. It captures sunlight and Carbon dioxide from the atmosphere and undergoes chemical reaction to produce food and Oxygen as a product. Since, there is no way to store the Oxygen gas in the algae, it releases the Oxygen to the ocean and atmosphere. This oxygen is used by all the aquatic and land animals which live on earth.
compare and contrast potential and kinetic energy
Potential energy is stored energy due to an object's position or state, while kinetic energy is the energy of an object in motion. They differ in their state, with potential energy being at rest and kinetic energy being in action. However, both can be transformed into each other.
Explanation:Potential energy and kinetic energy are both forms of mechanical energy, but they are different in many ways. Potential energy is stored energy that an object has due to its position or state, like a rock perched at the top of a hill has gravitational potential energy. It has the potential to convert into kinetic energy but for now, it remains at rest.
On the other hand, kinetic energy is the energy of motion. An object in motion has kinetic energy— for example, a moving car or a flowing river has kinetic energy. Unlike potential energy, it is already in action. So the key difference is that potential energy is stored, while kinetic energy is in motion.
However, they are similar in that they both can be transformed into each other. For instance, when that rock on the hill begins to roll downhill, its potential energy is converting into kinetic energy.
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Two objects are dropped from a bridge an interval of 1.0s apart. Air resistance is negligible. During the time that both objects continue to fall, their separation increases.
Can someone explain why it increases, instead of staying constant?
If the two objects are dropped at 1.0 s time interval, their velocity will increase as they descend which will cause their separation distance to increase because velocity is directly proportional to displacement.
The rate at which each object falls is influenced by their respective weights. If air resistance is negligible, gravity will continue to pull each object until it hits the ground.
The influence of gravity will cause the following:
The speed of each object will increase gradually until it hits the ground, and each object will have maximum velocity before it hits the ground. This shows that velocity of each object increases as it descends.Velocity is directly proportional to displacement, as the velocity of each object increases, the distance between them will also increase.Thus, if the two objects are dropped at 1.0 s time interval, their velocity will increase as they descend which will cause their separation distance to increase because velocity is directly proportional to displacement.
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PLEASE ANSWER VERY IMPORTANT
A good scientist keeps an open mind to every idea and explanation, even if they do not appear to be relevant to the outcome of the current experiment
Which statement describes what happens when Bret runs up a flight of stairs?
His kinetic energy increases.
His potential energy decreases.
His kinetic energy is converted into potential energy.
His potential energy is converted into kinetic energy.
Answer:
The answer is C) His kinetic energy is converted into potential energy.
If an electric train is travelling south, which way is the smoke going?
Which of the following is true about the solar system?
A.
Most of the planets have moons.
B.
Earth is the only planet that has a moon.
C.
None of the planets have moons.
D.
All of the planets have moons.