Answer:
D
Explanation:
From the information given:
The angular speed for the block [tex]\omega = 50 \ rad/s[/tex]
Disk radius (r) = 0.2 m
The block Initial velocity is:
[tex]v = r \omega \\ \\ v = (0.2 \times 50) \\ \\ v= 10 \ m/s[/tex]
Change in the block's angular speed is:
[tex]\Delta _{\omega} = \omega - 0 \\ \\ = 50 \ rad/s[/tex]
However, on the disk, moment of inertIa is:
[tex]I= mr^2 \\ \\ I = (3 \times 0.2^2) \\ \\ I = 0.12 \ kgm^2[/tex]
The time t = 10s
∴
Frictional torques by the wall on the disk is:
[tex]T = I \times (\dfrac{\Delta_{\omega}}{t}) \\ \\ = 0.12 \times (\dfrac{50}{10}) \\ \\ =0.6 \ N.m[/tex]
Finally, the frictional force is calculated as:
[tex]F = \dfrac{T}r{}[/tex]
[tex]F= \dfrac{0.6}{0.2} \\ \\ F = 3N[/tex]
When an object vibrates it goes back and forth rapidly. How would you
describe this motion?
A: it goes below its starting point and back to its starting point
B: it goes passed its starting point in both directions
C: it will go back and fourth forever
D: it actually looks like spikey waves
Answer:
B) It appears to be SHM (simple harmonic motion) which is also the projection of an object moving in a circular path on either the x or y axes.
conduction happens because of
a)touching
b)liquid or gas
c)space
Explain why synovial joints have greater flexibility than fixed and cartilaginous joint.
Answer:Unlike fixed joints or cartilaginous joints, where the bones are connected by either connective tissue or cartilage, the bones in synovial joints are not directly joined by anything, which allows for a much greater range of motion.
Explanation: I got a 100% on my test
This force will cause the path of the particle to curve. Therefore, at a later time, the direction of the force will ____________. This force will cause the path of the particle to curve. Therefore, at a later time, the direction of the force will ____________. have a component along the direction of motion remain perpendicular to the direction of motion have a component against the direction of motion first have a component along the direction of motion; then against it; then along it; etc.
Answer:
have a component along the direction of motion that remains perpendicular to the direction of motion
Explanation:
In this exercise you are asked to enter which sentence is correct, let's start by writing Newton's second law.
circular movement
F = m a
a = v² / r
F = m v²/R
where the force is perpendicular to the velocity, all the force is used to change the direction of the velocity
in linear motion
F = m a
where the force is parallel to the acceleration of the body, the total force is used to change the modulus of the velocity
the correct answer is: have a component along the direction of motion that remains perpendicular to the direction of motion
Humans impact the Earth in good AND bad ways.
A) True
B) False
Answer:
True
Explanation:
yes we can see that we are helping animals but we create pollution which is very bad
A tennis ball with mass 57 g is travelling at 25 m/s [S] when it is intercepted by a tennis racquet for 4.0 ms after which the ball travels at 32 m/s [N]. What is the average force applied to the ball by the racquet?
Answer:
F = 812.25 N
Explanation:
Given (convert to SI units):
m = 57 g = 0.057 kg
[tex]v_{1}[/tex] = -25 [tex]\frac{m}{s}[/tex]
[tex]v_{2}[/tex] = 32 [tex]\frac{m}{s}[/tex]
t = 4 ms = 0.004 s
Find acceleration:
a = [tex]\frac{v_{2}-v_{1} }{t}[/tex] = [tex]\frac{32-(-25)}{0.004}[/tex] = 14250
Find force:
F = ma = 0.057(14250) = 812.25 N
Sparks occur when the electric field in air exceeds 3 x 106 N/C. This is because free electrons normally present in air are accelerated to such high speeds that their kinetic energy will overcome the potential energy holding other electrons to atoms. When those electrons rearrange themselves after such a collision, a flash of light is emitted. Let us suppose that the work done on an electron must give it an energy of 3 x 10-19 J to cause this ionization. How far does an electron involved in making in a spark travel through the air before it collides with an atom
Answer:
h = 5.38 10¹⁶ m
Explanation:
Let's start this exercise by assuming that all the potential energy of the electron is converted into kinetic energy, let's use the conservation of energy
starting point. Just before ionization
Em₀ = U = qE
final point. Right after ionization
Em_f = K = ½ m v²
Energy is conserved
Em₀ = Em_f
q E = ½ m v²
v² = 2qE / m
Now we can use the relationship between net work and kinetic energy
W_net = ΔK
net work is the work done by the electron minus the binding energy with the atom, called the work function, Ф = 3 10-19 J
W - Ф = K_f - K₀
we assume that the electron converts all its initial initial kinetic energy to be zero
W -Ф = ½ m v² - 0
W = ½ m v² +Ф
we substitute
W = 1/2 m 2qE/m + E
W = qE +Ф
W = 1.6 10⁻¹⁹ 3 10⁶ + 3 10⁻¹⁹
W = 4.8 10⁻¹³ + 3 10⁻¹⁹
W = 4.8 10⁻¹³ J
When the electron is in air, its kinetic energy can be transformed into gravitational potential energy
As the electron is in the air, all work is transformed into scientific energy
W = K
starting point Em₀ = K = W
end point Em_F = U = m g h
energy conservation Em₀ = Em_f
W = m g h
h = [tex]\frac{W}{mg}[/tex]
let's calculate
h = [tex]\frac{4.8 \ 10^{-13} x}{9.1 \ 10^{-31} \ 9.8 }[/tex]
h = 5.38 10¹⁶ m
Electron involved in making in spark travel through the air before it collides with an atom will be at the distance of 5.38 10¹⁶ m.
What is an electric field?An electric field is an electric property that is connected with any location in space where a charge exists in any form. The electric force per unit charge is another term for an electric field.
Let's begin this exercise by assuming that all of the electron's potential energy is turned into kinetic energy, and then we'll apply the law of conservation of energy.
Energy before ionization;
[tex]\rm Em_0 = U = qE[/tex]
Energy after ionization;
[tex]Em_f = K = \frac{1}{2} mv^2[/tex]
From the law of conservation of energy principle;
[tex]Em_0 = Em_f \\\\ q E =\frac{1}{2} m v^2\\\\ v^2 = \frac{2qE }{m}[/tex]
The relationship between net work and kinetic energy;
[tex]W_{net} = \triangle K[/tex]
The work function is defined as net work, which is the work done by the electron minus the binding energy with the atom.
[tex]W - \phi = K_f - K_0[/tex]
[tex]W = K_f+ \phi[/tex]
[tex]W = \frac{1}{2} m \times \frac{2qE}{m} + E\\ \\W = qE + \phi \\\\ \rm W = 1.6 \times 10^{-19}\times 3 \tims 10^6 3 10⁶ +3 \times 10^{-19} \\\\ W = 4.8 \times 10^{-13}+ 3 \times 10^{-19}\\\\ W = 4.8 \times 10^{-13} J[/tex]
EMF at starting point;
[tex]\rm Em_0 = K = W[/tex]
EMF at the endpoint;
[tex]\rm Em_F = U = m g h[/tex]
From the law of conservation of energy principle;
[tex]Em_0 = Em_f \\\\ W = m g \\\\ h = \frac{W}{mg}\\\\\ h = \frac{4.8 \timjes 10^{-13}}{9.1 \times 10^{-31} \times 9.81 }\\\\ \rm h= 5.38 \times 10^{16}[/tex]
Hence electron involved in making in spark travel through the air before it collides with an atom will be at a distance of 5.38 10¹⁶ m.
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A moving man is lifting a box up an inclined plane. Halfway up he sets the box down and rests. Which of the following explains why the box does not slide back down the inclined plane?
a. The force of friction balances the force of gravity.
b. The force of gravity does not affect inclined planes.
c. The force of friction does not affect inclined planes.
d. The force of friction is less than the force of gravity.
Answer: A or B
Explanation: I’m guessing that they even each other out depending on the incline, gravity will help keeping it in place
A 0.545-kg ball is hung vertically from a spring. The spring stretches by 3.56 cm from its natural length when the ball is hanging at equilibrium. A child comes along and pulls the ball down an additional 5cm, then lets go. How long (in seconds) will it take the ball to swing up and down exactly 4 times, making 4 complete oscillations before again hitting its lowest position
Answer:
t = 9.52 s
Explanation:
This is an oscillatory motion exercise, in which the angular velocity is
w = [tex]\sqrt{ \frac{k}{m} }[/tex]
Let's use hooke's law to find the spring constant, let's write the equilibrium equation
F_e - W = 0
F_e = W
k x = m g
k = [tex]\frac{m g}{x}[/tex]
k = 0.545 9.8 /0.0356
k = 150 N / m
now the angular velocity is related to the period
W = 2π / T
we substitute
4π² T² = k /m
T = 4pi² [tex]\sqrt{ \frac{m}{k} }[/tex]
we substitute
T = 4 pi² [tex]\sqrt{ \frac{0.545}{150} }[/tex]
T = 2.38 s
therefore for the spring to oscillate 4 complete periods the time is
t = 4 T
t = 4 2.38
t = 9.52 s
Which action can knowing the "Three Rs lead a person to do?
A) resolving conflicts
B) helping one's family create a disaster plan
C)staying safe in a natural disaster
D)protecting the environment
Answer:
d
Explanation:
Let's explore the assumptions we made. Look closely at Jessie's motion as she runs. In calculating her power output, we assumed that the work she did was equal to the work done by the force of gravity on her body. Do you think that is a good assumption
Answer:
No, it is not a good assumption
Explanation:
From the given information:
The work Jessie did was quite more than the work done by the force of gravity. This is because the gravity of the force on her body is perpendicular to its motion and the work done by Jessie is due to the muscular force of her body. Hence, the total power she produced is more than the calculated amount.
Look at this attached photo
Answer:
C) Kinetic energy
Explanation:
Since the skateboarder is ALREADY going down the hill, he is using kinetic energy.
Kinetic energy is when you're moving and in motion
what do solar winds and the earths magnetic field create
Answer:
bc earth rotates
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Explanation:
Answer:
The interaction between the solar wind and Earth's magnetic field, and the influence of the underlying atmosphere and ionosphere, creates various regions of fields, plasmas, and currents inside the magnetosphere such as the plasmasphere, the ring current, and radiation belts.
Explanation:
stainless steel, tell us about its properties and what should be taken into account when using it?
Plz answer asap I need all of the answer
Answer:
Turned up side down
Explanation:
Which of the following is NOT true about
newspaper weather maps?
A. They report the temperature of the area in degrees
Fahrenheit.
B. They let you know how much precipitation to expect.
C. They provide more detail than weather service maps.
D. They tell you about the warm and cold air fronts.
You serve a basketball with a mass of 5 kg. If the ball leaves your hand at 30 m/s what is
the kinetic energy?
A) 150 joules
B) 2,250 joules
C) 75 joules
ʕ•ᴥ•ʔhi how are you ？
Answer:
I’m not okay . Me and my bf are bickering once again
1. Although mercury is a metal, it is a liquid at room temperature. Mercury melts at about -39°C. If
the temperature of a block of mercury starts at -54°C and increases by 22°C, does the mercury melt?
Explain your answer.
Answer:
I think so because if it starts at a low temperature for that material, it should melt when you bring it up to that temperature.
Answer: Mercury
Explanation: Mercury is kinda like the opposite of regular semi-liquid. For ice to melt you need Fahrenheit to melt ice into water while you need Celsius to melt mercury.
sound wave of a wave length of 0.56 meters if its speed is 280 m/s what is the wave frequency
Answer:
500 Hz
Explanation:
Formula for finding wave frequency is,
f = c/λ
f = frequency
c = speed (m/s)
λ = wave length (m)
f = c/λ
f = 280/0.56
f = 500
∴ wave frequency is 500 Hz
What is the difference between a positively and negatively charged object?
Answer:
Positively charged objects have electrons; they simply possess more protons than electrons. Negatively charged objects have protons; it's just their number of electrons is greater than their number of protons.
The difference between a positively charged object and a negatively charged object is the number of protons and electrons. The imbalance in charge results into formation of charged objects.
What are Charged objects?
Charged objects have an imbalance of charge that is either more negative electrons than the positive protons or more positive protons than the negative electrons in the object. The neutral objects are those species which have a balance of charge with equal number of protons and electrons.
A positively charged object is formed when an atom has more protons than electrons. And, a negatively charged object is formed when an atom has more electrons than protons. As, electrons have a negative charge and protons have a positive charge.
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At the end of the passage, Sarah says to Emma, “You’re not the only one with tricks up your sleeves.” Explain what Sarah means by this. Use information from the passage to support your answer.
Answer:
Sarah plans to use trickery and cunning to get back at Emma. Sarah thinks she is smarter than Emma.
Explanation:
i think this is right i dont know tho
Which of the following is true of the deep
water layer of the ocean?
A. warmest and least dense of the ocean layers
B. experiences a rapid decrease in temperature
C. is warm in the summer and cold in the winter
D. cold all year round
does latitude has an effect on weight?
Answer:
I think so but i could be wrong..
Explanation:
Answer: yes it does
Explanation: Yes, you weigh less on the equator than at the North or South Pole, but the difference is small. Note that your body itself does not change. Rather it is the force of gravity and other forces that change as you approach the poles. These forces change right back when you return to your original latitude.
A roller coaster works by being hoisted to the top of the highest peak on the track and then released. As the roller coaster car moves along the track the energy gets converted back and forth between kinetic and gravitational potential energy. The entire time the roller coaster car is in motion air friction and friction in the wheels act to oppose the motion of the car. At which point during the ride is the total mechanical energy of the roller coaster car the greatest?
a. At the bottom of the first dip in the track when the car is moving the fastest.
b. When the car is exactly at half its original height half way through the ride.
c. At the top of the highest peak as the very start of the ride.
d. At the end of the ride as the car nears the station.
Answer:
a. At the bottom of the first dip in the track when the car is moving the fastest.
Explanation:
P.S - The exact question is -
The correct option is - a. At the bottom of the first dip in the track when the car is moving the fastest.
Reason -
From the diagram , we can see that the total mechanical energy of the roller coaster car is greatest At the bottom of the first dip in the track when the car is moving the fastest.
Disk A, with a mass of 2.0 kg and a radius of 70 cm , rotates clockwise about a frictionless vertical axle at 50 rev/s . Disk B, also 2.0 kg but with a radius of 50 cm , rotates counterclockwise about that same axle, but at a greater height than disk A, at 50 rev/s . Disk B slides down the axle until it lands on top of disk A, after which they rotate together. After the collision, what is their common angular speed (in rev/s) and in which direction do they rotate?
Answer:
w = - 197.5 rad / s
The negative sign indicates that the rotations are clockwise
Explanation:
To solve this exercise, let's use the concept of conservation of the angular number.
We create a system formed by the two discs, in this case the forces last the shock are internal
initial instant .. just before shock
L₀ = I₀ w₀ + I₁ w₁
instnte final. Right after crash
L_f = (I₀ + I1) w
angular momentum is conserved
I₀ w₀ + I₁ w₁ = (I₀ + I₁) w
w = I₀ w₀ + I₁ w₁ / Io + I1
The moment of inertia of a disk with an axis passing through its thermometric center
I₀ = ½ m² r₀²
I₁ = ½ m₁ r₁²
we substitute
I₀ = ½ 2.0 0.70²
I₀ = 0.49 kg m
I₁ = ½ 2.0 0.5²
I₁ = 0.25
₁
let's reduce the magnitudes the SI system
w₀ = -50 rev / (2pi rad / 1rev) = -314.15 rad / s
w₁ = 70 rev (2pi rad / 1rev) = 439.82 rad / s
we will assume that the counterclockwise turns are positive
w = -0.49 314.15 + 0.25 439.82 / (0.49 + 0.25)
w = (- 4.696 + 1.0995) 102) / 0.74
w = -197.75 + 0.25
w = - 197.5 rad / s
The negative sign indicates that the rotations are clockwise
Select all the correct answers.
Which statements about our solar system are false?
Our solar system is made up of the Sun and other objects that orbit the Sun.
The Sun is the only star in our solar system.
Dwarf planets have several other bodies in their path orbiting the Sun just as they do.
The Kuiper Belt is between Uranus and Neptune.
A large number of irregularly shaped comets are located in a vast ring between the orbits of Mars and Jupiter.
D and E are false.
A, B, and C are true.
Answer:
- Our solar system is made up of the Sun and other objects that orbit the Sun.
- The Sun is the only star in our solar system.
- Dwarf planets have several other bodies in their path orbiting the Sun just as they do.
Explanation:
plato
If a weather service map has a circle that
is shaded completely in, what does that
mean about the cloud cover in that area?
A. There is 100% cloud cover in that area.
B. There is 0% cloud cover in that area.
C. There is a good chance of rain.
D. There are sunny skies.
Answer:
A. There is 100% cloud cover in that area.
Explanation:
Cloud cover is recorded on weather charts by shading in parts of the circle.
If there are no clouds, the circle is left white and if the sky is completely covered in cloud, the circle is shaded completely in which means 100% cloud cover in that area.
What is the work done by the 200.-N tension shown if it is used to drag the 150-N crate 25 m across the floor at a constant speed?
Answer:
0 J
Explanation:
Work equals force times distance, but the force is zero because the crate being dragged will have zero acceleration. Force equals mass times acceleration and since acceleration is zero, force has to equal zero as well. Since the force is zero, the work required also has to be zero.
What is characteristic of a good insulator?
A. Electrons are usually not moving at all.
B. Electrons are free to move around.
C. Electrons are semi-free to move around.
D. Electrons are tightly bound to the nuclei.
Answer:
D. Electrons are tightly bound to the nuclei.
Explanation:
In an insulator, the electrons of the outer most shell are bound with a very high electrostatic forces coming from the nucleus of each atom so electrons cannot flow around all atoms making up the material as in a conductor.
The characteristic of a good insulator is Electrons are tightly bound to the nuclei. (option d)
In a good insulator, electrons are tightly bound to the nuclei of their atoms. This means that they are not free to move around within the material, unlike conductors where electrons are relatively loosely bound and can move freely. Due to this strong binding, electrons in insulating materials cannot carry an electric charge or energy easily from one atom to another.
When an electric field is applied to an insulator, the electrons may experience a small displacement within their respective atoms, but they generally do not move from one atom to another or flow through the material like they would in a conductor. As a result, insulators prevent the flow of electric current and are used to isolate or protect conductive elements from accidental contact.
So, the correct answer is D. Electrons are tightly bound to the nuclei.
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