1. The nearest distance of distinct vision of
a hypermetropial person is 60 cm. If this
distance is reduced by 20 cm by using
spectacles. What is the nature and focal
length of the lens?
a. +30 cm b. +35 cm
-30 cm
d. -40 cm
c.
Answer:
The focal length of the lens is +30 and it is a convex lens.
Explanation:
Given that,
The nearest distance of distinct vision of a hypermetropial person is 60 cm, v = -60 cm
The distance is reduced by 20 cm, u = -20 cm
We need to find the nature and focal length of the lens.
Let f be the focal length of the lens. Using lens formula,
\(\dfrac{1}{v}-\dfrac{1}{u}=\dfrac{1}{f}\\\\\dfrac{1}{f}=\dfrac{1}{(-60)}-\dfrac{1}{(-20)}\\\\f=+30\ cm\)
So, the focal length of the lens is +30 and it is a convex lens.
A 2.56×104-kg rocket blasts off vertically from the earth's surface with a constant acceleration. During the motion considered in the problem, assume that g remains constant. Inside the rocket, a 13.6-N instrument hangs from a wire that can support a maximum tension of 27.5 N .
a)Find the minimum time for this rocket to reach the sound barrier (330m/s)
without breaking the inside wire.
b)Find the maximum vertical thrust of the rocket engines under these conditions.
c)How far is the rocket above the earth's surface when it breaks the sound barrier?
a. The minimum time for the rocket to reach the sound barrier is 33.67 seconds.
b. The maximum vertical thrust of the rocket engines under these conditions is 250,893.6 N.
c. The rocket is 5548.1 meters above the Earth's surface when it breaks the sound barrier.
To solve this problem, we'll use Newton's second law of motion (F = ma) and consider the forces acting on the rocket and the instrument inside.
Calculating the minimum time for the rocket to reach the sound barrier without breaking the inside wire.
a) Minimum time to reach the sound barrier:
Given:
Mass of the rocket (m) = 2.56 × \(10^4\) kg
Acceleration due to gravity (g) = 9.8 m/\(s^2\)
Maximum tension the wire can support (T_max) = 27.5 N
Weight of the instrument (W) = mass of the instrument × acceleration due to gravity = 13.6 N
The forces acting on the instrument inside the rocket are its weight (W) and the tension in the wire (T). At maximum tension, the net force on the instrument is zero.
T - W = 0
T = W
Therefore, the maximum tension in the wire is equal to the weight of the instrument, which is 13.6 N.
Now, let's determine the acceleration of the rocket. The total force acting on the rocket is the sum of the rocket's weight (mg) and the tension in the wire (T).
F_total = mg + T
F_total = (2.56 × \(10^4\) kg)(9.8 m/\(s^2\)) + 13.6 N
F_total = 250,880 N + 13.6 N
F_total = 250,893.6 N
Since we're assuming the rocket's acceleration is constant.
we can use Newton's second law:
F_total = ma
250,893.6 N = (2.56 × \(10^4\) kg)a
Solving for acceleration:
a = 250,893.6 N / (2.56 × \(10^4\) kg)
a ≈ 9.8 m/\(s^2\)
The acceleration of the rocket is approximately 9.8 m/\(s^2\), which is the same as the acceleration due to gravity.
To find the minimum time to reach the sound barrier, we can use the following equation of motion:
v = u + at
where,
v = final velocity (sound barrier velocity = 330 m/s)
u = initial velocity (which is zero since the rocket starts from rest)
a = acceleration
t = time
330 m/s = 0 + (9.8 m/\(s^2\))t
Solving for t:
t = 330 m/s / 9.8 m/\(s^2\)
t ≈ 33.67 s
Therefore, the minimum time for the rocket to reach the sound barrier without breaking the inside wire is approximately 33.67 seconds.
b) Maximum vertical thrust of the rocket engines:
The maximum vertical thrust of the rocket engines is equal to the total force acting on the rocket, which we calculated earlier:
Maximum vertical thrust = F_total
Maximum vertical thrust ≈ 250,893.6 N
Therefore, the maximum vertical thrust of the rocket engines under these conditions is approximately 250,893.6 N.
c) Distance above the Earth's surface when breaking the sound barrier:
To determine the distance above the Earth's surface when breaking the sound barrier, we can use the following equation of motion:
s = ut + (1/2)at^2
where,
s = distance
u = initial velocity (which is zero)
a = acceleration
t = time it takes to reach the sound barrier (33.67 s).
s = 0 + (1/2)( 9.8 m/\(s^2\))\((33.67 s)^2\)
s = (\(4.9 m/s^2\))(1132.8289 \(s^2\))
s ≈ 5548.1 m
Therefore, the rocket is approximately 5548.1 meters (or 5.55 kilometers) above the Earth's surface when it breaks the sound barrier.
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Question 21 of 25
Which statement best describes one way that molecules differ from atoms?
A. A molecule can contain two atoms of the same element.
B. Only a molecule can be the smallest particle of a certain element.
C. Only a molecule can be broken down into two or more different
elements.
D. A molecule can contain a nucleus about which its electrons orbit.
SUBM
Answer is A
Answer:
A
Molecule is basically made of an atom or group of atoms of same or different element and it is definitely possible for it to be made up of two atoms of same element
Can anyone please help me
To solve this problem, we can use Coulomb's law, which states that the electric force between two point charges is proportional to the product of their charges and inversely proportional to the square of the distance between them.
We can then use the electric force to find the electric field at the location of q3 and the initial acceleration of q3.
a) To find the electric field at the location of q3, we can first find the electric force on q3 due to q1 and q2 and then use the definition of the electric field, which is the electric force per unit charge. The electric force on q³ due to q¹ and q² is:
F1 = k x q¹ x q³/ r1²
F2 = k x q² x q³ / r2²
where r¹ and r² are the distances from q¹ and q² to q³, respectively, and k is Coulomb's constant.
Since q³ is equidistant from q¹ and q², we have r¹ = r² = 0.20 m. Substituting the given values, we get:
F1 = (9.0 x 10⁹ N-m²/C²) x (4.0 x 10⁻⁶ C) x (2.0 x 10⁻⁶C) / (0.20 m)² = 1.8 N
F2 = (9.0 x 10⁹ N-m⁻²/C²) x (-6.0 x 10⁻⁶ C) x (2.0 x 10⁻⁶C) / (0.20 m)² = -5.4 N
The negative sign of F2 indicates that the force on q³ due to q² is in the opposite direction to the force due to q¹.
The net electric force on q3 is the vector sum of the forces due to q1 and q2:
Fnet = F1 + F2 = 1.8 N - 5.4 N = -3.6 N
The electric field at the location of q³ is then:
E = Fnet / q³ = (-3.6 N) / (2.0 x 10⁻⁶ C) = -1.8 x 10⁻⁶N/C
The negative sign of the electric field indicates that the field is directed towards q².
b) To find the initial acceleration of q³, we can use Newton's second law, which states that the net force on an object is equal to its mass times its acceleration:
Fnet = ma
where m is the mass of q³ and a is its initial acceleration.
Substituting the given values, we get:
-3.6 N = (2.0 x 10⁻⁶ kg) x a
Solving for a, we get:
a = -1.8 x 10³ m/s²
The negative sign of the acceleration indicates that it is directed towards q².
c) The direction of the initial acceleration of q³ is towards q².
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The largest stars we know of have masses of a little over 1035 kilograms, while the lowest mass stars have masses of about 1032 kilograms. How many times more massive are the most massive stars than the lowest mass stars?
Group of answer choices
a thousand times more massive.
a hundred times more massive.
ten times more massive.
ten thousand times more massive
Answer:
the bigger stars tend to be hotter and burn through their fuel more quickly than smaller stars they also tend to ether be turned into a black hole or a huge nebula with a neutron star the smaller stars have a tendency to go through their fuel slower and don't get as hot as big stars until the red giant stage.
Explanation:
Two drums are rolling down a hill. The drums are the same size and mass.
Drum #1 has most of its mass concentrated at the rim, while drum #2 has
most of its mass concentrated in the center. Which of the following
statements are correct? Select all that apply.
Drum #1 will reach the bottom of the hill first because its moment of inertia is
greater.
Drum #1 will have a greater center of mass speed and reach the bottom of the
hill first.
Drum #2 will have a greater center of mass speed and reach the bottom of the
hill first.
Drum #2 will reach the bottom of the hill first because its moment of inertia is
smaller.
Hi there!
Drum #2 will have a greater center of mass speed and reach the bottom of the hill first.
The moment of inertia can be thought of as inertia for rotation.
If mass is concentrated at the rim, the drum has a GREATER moment of inertia compared to if the mass is more concentrated towards the center.
Using the Rotational Equivalent of Newton's Second Law:
\(\Sigma \tau = I\alpha\)
**Sum of torques = Moment of inertia * angular acceleration
From this equation, we know that if 'I' increases, 'α' decreases, and thus, the speed of the object's center of mass decreases and it will reach the bottom later.
Therefore, drum #2 with the smaller moment of inertia (mass concentrated at the center) will have a greater angular acceleration ⇒ greater center of mass speed ⇒ read the bottom first.
how does the rocket engine work?
Answer:
The vacuum of space
Heat management problems
The difficulty of re-entry
Orbital mechanics
Micrometeorites and space debris
Cosmic and solar radiation
The logistics of having restroom facilities in a weightless
Explanation:
The half-life of a radioactive isotope is 210 d. How many days would it take for the decay rate of a sample of this isotope to fall to 0.58 of its initial rate?
It would take approximately 546 days for the decay rate of the sample of this radioactive isotope to fall to 0.58 of its initial rate.
1. The decay rate of a radioactive isotope is proportional to the number of radioactive atoms present in the sample at any given time.
2. The decay rate can be expressed as a function of time using the formula: R(t) = R₀ * \(e^{(-\lambda t\)), where R(t) is the decay rate at time t, R₀ is the initial decay rate, λ is the decay constant, and e is the base of the natural logarithm.
3. The half-life of a radioactive isotope is the time it takes for half of the radioactive atoms in a sample to decay. In this case, the half-life is given as 210 days.
4. Using the half-life, we can find the decay constant (λ) using the formula: λ = ln(2) / T₁/₂, where ln(2) is the natural logarithm of 2 and T₁/₂ is the half-life.
5. Substituting the given half-life into the formula, we have: λ = ln(2) / 210.
6. Now, we need to find the time it takes for the decay rate to fall to 0.58 of its initial rate. Let's call this time "t".
7. Using the formula for the decay rate, we can write: 0.58 * R₀ = R₀ * e^(-λt).
8. Simplifying the equation, we get: 0.58 = \(e^{(-\lambda t\)).
9. Taking the natural logarithm of both sides, we have: ln(0.58) = -λt.
10. Substituting the value of λ from step 5, we get: ln(0.58) = -(ln(2) / 210) * t.
11. Solving for t, we have: t = (ln(0.58) * 210) / ln(2).
12. Evaluating the expression, we find: t ≈ 546.
13. Therefore, it would take approximately 546 days for the decay rate of the sample of this radioactive isotope to fall to 0.58 of its initial rate.
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Perform an experiment in which you roll a ball 43,700 cm before it comes to a stop. Write this measurement in scientific notation
The number 43,700 cm when written by the use of the scientific notation will be written as 4.37 * 10^4 cm.
What is the scientific notation?The scientific notation involves writing a number in such a way that it does not involve a lot of digits. This methods helps us to save space that would have been used to write long digits.
Hence, the number 43,700 cm when written by the use of the scientific notation will be written as 4.37 * 10^4 cm.
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Can anyone help me answer this question?
The density of gold is 19.3 g/cm^3. What is the value in kilogram per cubic meter? Show working.
19.3 gcm3 19.3 g c m 3 is equivalent to 19300 kgm3 due to the decimal place shifting due to the conversion being in metric measurements.
Density: What does that mean?The amount of objects, including people, animals, plants, and other living things, that are present in a region is known as the density. The number of objects is divided by the area to determine density. The number of inhabitants in a nation divided by its size, measured in square kilometers or miles, is the population density of that nation.
In its most basic form, what is density?In reference to the amount of matter contained in a thing, density refers to how much volume the object or substance occupies.
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What is the minimum resultant possible when adding a 5-N force to an 8-N force?
A.5N
B.8 N
C.40 N
The minimum resultant force possible when adding a 5-N force to an 8-N force is 3 N.
option D.
What is the minimum resultant force of 5 N and 8 N?
The minimum resultant force is obtained when the two forces are parallel to each and the angle between them is 0 degrees and the magnitude of the resultant force is calculated as follows;
R² = 5² + 8² - ( 2 x 5 x 8 ) x cos ( 0 )
R² = 89 - 80
R² = 9
R = √ ( 9 )
R = 3 N
Thus, the minimum possible resultant force is obtained when the two forces are parallel to each other.
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The complete question is below:
What is the minimum resultant possible when adding a 5-N force to an 8-N force?
A.5N
B.8 N
C.40 N
D. 3 N
Which describes the reaction of a substance to form one or more new substances?
a physical change
a chemical change
a change of state
What is the total charge of barium oxide?
a) A bomb, initially at rest, explodes into several pieces. (a) Islinear momentum of the system conserved? (b) Is kinetic energy of the system conserved? Explain
(a) The linear momentum of the system is conserved due to the absence of external forces. (b) The kinetic energy of the system is generally not conserved in an explosion due to energy transfers and losses associated with the process.
(a) According to the principle of conservation of momentum, the total momentum of an isolated system remains constant if no external forces act upon it. In the given scenario, the bomb is initially at rest, which means the total momentum of the system is zero before the explosion. After the explosion, the bomb fragments move in different directions, but their individual momenta add up to zero. Thus, the total momentum of the system remains conserved.
(b) In an explosion, a significant amount of potential energy stored in the bomb is rapidly converted into kinetic energy of the fragments. As the bomb explodes, the fragments gain kinetic energy, resulting in an increase in the total kinetic energy of the system. Additionally, the explosion may cause the fragments to collide with other objects or experience air resistance, leading to energy losses in the form of heat, sound, or work done against external forces. These energy losses further prevent the conservation of kinetic energy.
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một bánh xe bao gồm 1 vành bánh xe có khối lượng M=5kg và 8 căm, mỗi căm có khối lượng m=1kg và dài R=0,4m, đang lăn trên mặt đường phẳng với vặn tốc góc w=80rad/s
Tính động năng toàn phần của bánh xe
Answer:
What is your country I don't understand
Draw a labelled diagram to show how a pure spectrum with white light maybe produced.
Answer:
The below diagram shows pure spectrum with white light
Explanation:
Describe and explain motion due to uniform velocity in one direction and uniform acceleration in a perpendicular direction
Answer: you have to divide and multiple fam
Explanation:
An artillery shell is fired at a target 200 m above the ground. When the shell is 100 m in the air, it has a speed of 100 m/s. What is its speed when it hits its target?
The speed of the artillery shell when it hits its target is 100 m/s.
Given:
Initial vertical displacement (y) = 200 m
Vertical displacement at 100 m in the air (y') = 100 m
Final velocity in the vertical direction (vy') = 0 m/s (at the highest point of the trajectory)
Using the equation for vertical displacement in projectile motion:
y' = vy^2 / (2g),
where g is the acceleration due to gravity (approximately 9.8 m/s^2), we can solve for the initial vertical velocity (vy).
100 m = vy^2 / (2 * 9.8 m/s^2),
vy^2 = 100 m * 2 * 9.8 m/s^2,
vy^2 = 1960 m^2/s^2,
vy = sqrt(1960) m/s,
vy ≈ 44.27 m/s.
Now, since the horizontal motion is independent of the vertical motion, the horizontal speed of the shell remains constant throughout its trajectory. Therefore, the speed of the shell when it hits its target is 100 m/s.
Hence, the speed of the artillery shell when it hits its target is 100 m/s.
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A boy starts working front point A and walks a love fowards north and stops at point Now, he furns 136. to his right and walks loleme to reach a point c. what is distance betweee A & C ?
Answer:
Without knowing the actual distances involved, it's difficult to give a specific answer. However, we can use the information given in the question to determine the distance between points A and C using the Pythagorean theorem.
Let's assume that the boy walked a distance of x units from point A to point B, and a distance of y units from point B to point C. Then we can use the following diagram:
C
|
y |
| | x
|-----------B
|
|
A
According to the problem, the boy first walked a certain distance x in a direction that is not specified (we only know that it's forward and north). Then he turned 136 degrees to his right and walked a distance y to reach point C. Since the turn was to the right, the boy turned towards the east, so we can draw a line from point B towards the right to represent this change in direction.
Now we can apply the Pythagorean theorem to find the distance between points A and C:
AC² = AB² + BC²
We know that AB = x, and we need to find BC. To do so, we can use trigonometry. Since the boy turned 136 degrees to his right, he ended up facing 180 - 136 = 44 degrees east of north. This means that the angle between BC and AB is 90 - 44 = 46 degrees.
Using trigonometry, we can express BC in terms of y and the tangent of the angle 46 degrees:
tan(46) = BC / y
BC = y tan(46)
Substituting this expression for BC into the Pythagorean theorem equation, we get:
AC² = x² + (y tan(46))²
Simplifying:
AC² = x² + y² tan²(46)
We can calculate tan²(46) using a calculator or a table of trigonometric functions. Let's assume that tan²(46) is equal to 1.470. Then we have:
AC² = x² + 1.470y²
To find the distance between A and C, we need to take the square root of both sides of the equation:
AC = sqrt(x² + 1.470y²)
Without more information about the distances involved, we cannot compute the actual numerical value of AC.
What is the reaction force when baseball catcher catches and stops a baseball?
When the baseball catcher catches a baseball, then ... during the time that he is slowing the ball down and stopping it ... he is exerting an action force with his glove on the ball, and the ball is exerting an equal and opposite reaction force on his glove.
Define "increased productivity" in terms of the number of tasks and the amount of time.
Answer:
The greater the amount of output for a given unit of input, the higher the overall productivity. Businesses generally aim to improve productivity over time to maintain competitiveness and increase the business's profitability. Individuals are familiar with the idea of productivity in their own lives.
Nowton's third law refers to 'action reaction forces*. These forces are
always:
equal in magnitude but opposite in direction
a 30.0 kg child starting from rest slides down a water slide with the vertical height of 10.0 m what is the child speed (a )halfway down the slides vertical distance and (b) 3/4 of the way down
We know that
• The mass is m = 30.0 kg.
,• The vertical height is h = 10.0 m.
(a)We have to use the conservation of energy theorem, which states that mechanical energy is constant all the time. Also, halfway down means a height of 5.0 m. It's important to know that at the top the total energy is potential, while halfway is distributed as kinetic and potential, the expression below shows this
\(E_{p1}=E_{k1}+E_{p2}\)Then, using the definition of each energy, we have
\(mgh_1=\frac{1}{2}mv^2+mgh_2\)Now, we use the given values to find the speed.
\(\begin{gathered} \text{mgh}_1=m(\frac{1}{2}v^2+gh_2) \\ gh_1=\frac{1}{2}v^2+gh_2 \\ 9.81m/s^2\cdot10m=\frac{1}{2}v^2+9.81m/s^2\cdot5m \\ 98.1m^2/s^2=\frac{1}{2}v^2+49.05m^2/s^2 \\ 98.1m^2/s^2-49.05m^2/s^2=\frac{1}{2}v^2 \\ 2\cdot49.05m^2/s^2=v^2 \\ v=\sqrt[]{98.1m^2/s^2} \\ v\approx9.9m/s \end{gathered}\)Therefore, the speed of the child halfway down is 9.9 meters per second.(b)In this case, we just have to use as the second height of the equation the magnitude 2.5 meters because that's 3/4 of the way down. So, let's use the same process and expression
\(\begin{gathered} gh_1=\frac{1}{2}v^2+gh_2 \\ 9.81m/s^2\cdot10m=\frac{1}{2}v^2+9.81m/s^2\cdot2.5m \\ v=\sqrt[]{2(98.1m^2/s^2-24.53m^2/s^2)} \\ v\approx12.1m/s \end{gathered}\)Therefore, the speed of the child 3/4 of the way down is 12.1 meters per second.9. A yo-yo is moving in a horizontal circle of radius R. the yo-yo has a mass of 0.250 kg has a speed of 9 m/s and experience this a centripetal force of 26.6 N what is the radius of the circle that the yo-yo is moving in?
ANSWER:
B. 0.761 meters
STEP-BY-STEP EXPLANATION:
Given:
Mass (m) = 0.250 kg
centripetal force (Fc)= 26.6 N
Speed (v) = 9m/s
We have that the centripetal force can be calculated using the following formula:
\(F_c=\frac{m\cdot v^2}{r}\)We substitute each value and solve for the radius, just like this:
\(\begin{gathered} r=\frac{m\cdot v^2}{F_c} \\ r=\frac{0.25\cdot9^2}{26.6} \\ r=\frac{0.25\cdot81}{26.6} \\ r=0.761\text{ m} \end{gathered}\)The radius is equal to 0.761 meters
Which of the following is NOT a scientific hypothesis?
A. Neon atoms emit red light.
B. There is an attractive force between the earth and moon.
C. Halle Berry is attractive.
D. Summer days are hottest
E. The sky is blue.
The following statement is not a scientific hypothesis:
C. Halle Berry is attractive.
A scientific hypothesis is a proposed explanation for an observation or pattern in nature that can be tested through further investigation and experimentation. It should be testable, falsifiable, and based on evidence.
Neon atoms emit red light. This is a scientific hypothesis that can be tested and confirmed by looking at the spectrum of light emitted by neon atoms.
B. There is an attractive force between the earth and moon. This is a scientific hypothesis that can be tested and confirmed by measuring the force of gravity between the earth and moon.
D. Summer days are the hottest of the year. This is a scientific hypothesis that can be tested and confirmed by collecting temperature data during the summer months.
E. The sky is blue. This is a scientific hypothesis that can be tested and confirmed by observing the sky under different atmospheric conditions.
The statement "Halle Berry is attractive" is a subjective opinion that cannot be tested or confirmed through scientific investigation, hence it is not a scientific hypothesis. Attractiveness, as a concept, can vary widely based on personal, cultural, and social factors.
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what is Shortening melting
physical property
chemical change
chemical property
physical change
What is the difference between an empirical issue and ethical issue? (sociology question)
Answer:
When it comes to research questions, sociologists are best equipped to answer empirical questions. —those that can be answered by real experience in the real world—as opposed to ethical questions. —questions about which people have moral opinions and that may not be answerable in reference to the real world.
Explanation:
A person standing on the roof of a building drops a 0.125 Kg ball on the ground. A
child on eight floor saw the ball passing with a speed of 33.1 m/s. The first floor of the building
is 12.0 m high and each successive floor is 8.00 m high. Determine the total numbers of floors
in the building. How fast was the ball falling just before it hit the ground? What was its kinetic
energy just before it hit the ground?
Answer:
V = a t velocity after time t
t = 33.1 / 9.80 = 3.38 sec (time ball had been falling)
S = 1/2 a t^2 = 55.9 m
So the ball had been falling for 7 * 8 = 56 m
The child was 7 floors from the top
Since he was on the eight floor the floors below him were
7 * 8 + 12 = 68 m total floors below child
68 + 56 = 124 m total height of building
Total floors in building = 7 + 7 + 1 = 15 floors
PE at top = KE at bottom
KE = m g h = .125 * 9.80 * 124 = 152 Joules
who was the first person to describe the earth as a magnet
Answer:
William Gilbert
Explanation:
first described the Earth as a giant dipole magnet 400 years ago. But, as Rod Wilson recounts, he did far more than this.
Answer:
william gilbert
Explanation:
first described the Earth as a giant dipole magnet 400 years ago. But, as Rod Wilson recounts, he did far more than this.
Marus traveled on a motorcylce distance of 1,298meters north to get to the nearest shopping center. He then turned back south and rode another 1,250 meters to meet his friend. What was his displacement?
Answer:
48 meters north
Explanation:
If you measure the distance between the point Marus started and the point where they stopped after traveling 1,250 meters back south, you get 48 meters. To make this a displacement quantity, you add 'north' to the end and get 48 meters north, considering this was the initial direction of the motorcycle.