Correct question is;
A ballet dancer spins with 2.4 rev/s with her arms outstretched,when the moment of inertia about axis of rotation is I. With her arms folded,the moment of inertia about the same axis becomes 0.6I about the same axis. Calculate the new rate of spin.
Answer:
4 rev/s
Explanation:
We are given;
Initial Angular velocity; ω_i = 2.4 rev/s
Initial moment of inertia; I_i = I
Final moment of inertia; I_f = 0.6I
From conservation of angular momentum, we have;
I_i × ω_i = I_f × ω_f
Where ω_f is the new rate of spin.
Thus, let's make it the subject to get;
ω_f = (I_i × ω_i/I_f)
Plugging in relevant values, we have;
ω_f = (I × 2.4/0.6I)
I will cancel out to give;
ω_f = 2.4/0.6
ω_f = 4 rev/s
5.An ice skater pushes against a wall with a force of 59 N. Ignoring friction, if the ice skater has
a total mass of 79 kg, what is the magnitude of his acceleration?
(A) 0.75 m/s2
(B) 1.3 m/s2
(C) 21 m/s2
Answer:
Answer: (A) 0.75 m/s^2
Explanation:
The Second Newton's law states that an object acquires acceleration when an external unbalanced net force is applied to it.
That acceleration is proportional to the net force and inversely proportional to the mass of the object.
It can be expressed with the formula:
[tex]\displaystyle a=\frac{F_n}{m}[/tex]
Where
Fn = Net force
m = mass
The ice skater pushes against a wall with a force of 59 N. The wall returns the force and the skater now has a net force of Fn=59 N that makes him accelerate. Being m=79 kg the mass of the skater, the acceleration is:
[tex]\displaystyle a=\frac{59}{79}[/tex]
[tex]a = 0.75\ m/s^2[/tex]
Answer: (A) 0.75 m/s^2
What is a push or pull that one object excerpts on another object?
Answer:
Force
Explanation:
Must physics always be explained by math?
Answer:
Because Physics is mainly composited of math
Explanation:
If you really think about it the only way any science works is off maths, whether that be measuring the amount of NaOH to put into a solution or determening the amount of sugar you want in a cake it all relys on maths
If the pressure in a gas is doubled while its volume is held constant, by what factor do vrms change
Answer is given below
Explanation:
given data
pressure = double
volume = constant
solution
As we know that an Average velocity and rms velocity is directly proportional to square root of PV ..................1
so if we take P is doubled while keeping V constant
than Velocity increases by a factor [tex]\sqrt{2}[/tex]
so that Factor = 1.414 for both the cases
pls help ASAP
will marking brainliest
Take gravitational constant g = 10 m/s2.
1) The work function for calcium is 2.9 ev. If we shine on the surface made of calcium with a
light of 420 nm wavelength, answer the following questions:
a) Find the energy of the incident photon.
b) Is this energy enough for an electron to leave the atom and if so what is its
maximum energy?
Answer:
a. 4.733 × 10⁻¹⁹ J = 2.954 eV b i. yes ii. 0.054 eV = 8.651 × 10⁻²¹ J
Explanation:
a. Find the energy of the incident photon.
The energy of the incident photon E = hc/λ where h = Planck's constant = 6.626 × 10⁻³⁴ Js, c = speed of light = 3 × 10⁸ m/s and λ = wavelength of light = 420 nm = 420 × 10⁻⁹ m
Substituting the values of the variables into the equation, we have
E = hc/λ
= 6.626 × 10⁻³⁴ Js × 3 × 10⁸ m/s ÷ 420 × 10⁻⁹ m
= 19.878 × 10⁻²⁶ Jm ÷ 420 × 10⁻⁹ m
= 0.04733 × 10⁻¹⁷ J
= 4.733 × 10⁻¹⁹ J
Since 1 eV = 1.602 × 10⁻¹⁹ J,
4.733 × 10⁻¹⁹ J = 4.733 × 10⁻¹⁹ J × 1 eV/1.602 × 10⁻¹⁹ J = 2.954 eV
b. i. Is this energy enough for an electron to leave the atom
Since E = 2.954 eV is greater than the work function Ф = 2.9 eV, an electron would leave the atom. So, the answer is yes.
ii. What is its maximum energy?
The maximum energy E' = E - Ф = 2.954 - 2.9
= 0.054 eV
= 0.054 × 1 eV
= 0.054 × 1.602 × 10⁻¹⁹ J
= 0.08651 × 10⁻¹⁹ J
= 8.651 × 10⁻²¹ J
Every force has a specific and identifiable cause called a(n)...............
1- agent
2- vector
3- system
4- direction
A waves is set up in a stretched string by plunking it. The velocity of the waves depends on the tensions. Derived the dimensional equation
Answer:
justin
Explanation:
justin
Which type of electromagnetic radiation is useful in communications
technology?
Answer:
radio waves
Explanation:
Radio waves are used for communication such as television and radio. Radio waves are transmitted easily through air. They do not cause damage if absorbed by the human body, and they can be reflected to change their direction. These properties make them ideal for communications.
Answer:
The answer is radio waves.
Explanation:
I took AP EX quiz.
What is the second velocity of the car with three washers at the 0.50 meter mark? o ese m/s
Answer:
The first velocity is 0.19
The second velocity is 0.45
Explanation:
The current in a coil with a self inductance of 1.5 mH increases from 0 to 1.0 A in a tenth of a second. What is the induced emf in the coil
Answer:
the induced emf in the coil is 15 mV.
Explanation:
Given;
self inductance, L = 1.5 mH = 1.5 x 10⁻³ H
change in current = dI = 1.0 A
change in time, dt = 1/10 = 0.1
The induced emf is calculated as;
[tex]Induced \ EMF = L (\frac{dI}{dt} )\\\\Induced \ EMF = 1.5 \times 10^{-3}\ (\frac{1}{0.1} )\\\\Induced \ EMF = 1.5 \times 10^{-3} \ \times \ 10\\\\Induced \ EMF = 15 \times 10^{-3} \ V\\\\Induced \ EMF = 15 \ mV[/tex]
Therefore, the induced emf in the coil is 15 mV.
a bag of cement is pulled along a horizontal plane by a constant force of 15n calculate the work done in moving the bag through a distance of 20m
Answer:
300J
Explanation:
Given parameters:
Constant force = 15N
Distance = 20m
Unknown:
Work done = ?
Solution:
Work done is the force applied to move a body through a particular distance.
Work done = Force x distance
So;
Work done = 15 x 20 = 300J
A plot of land contains 3.6 acres. How many square meters does it contain? [1 acre = 43,560 ft?)
Answer:
It contains approximately 14,568.7 square meters
Explanation:
Area Units Conversion
There are several units to express the area of a shape:
[tex]cm^2,\ m^2,\ km^2,\ ft^2,\ in^2,\ acres, \ hectares[/tex]
The process of expressing the area from one unit to the other is called a conversion.
Specifically, we are interested in converting from acres to square meters. The rule to make the conversion is:
[tex]1 acre = 4,046.86\ m^2[/tex]
The plot of land has 3.6 acres, thus its area is:
[tex]3.6 * 4046.86 =14,568.696\ m^2[/tex]
It contains approximately 14,568.7 square meters
A student performs an experiment in which a 4kg object travels across a horizontal surface with an initial speed velocity of 6m/s and a 2kg object travels across a horizontal surface with an initial speed velocity of −3m/s. The objects travel toward each other and collide. Data collected from the experiment were used to create the velocity versus time graph shown that contains information about both objects before and after the collision. The positive direction is considered to be to the right. Which of the following statements are true regarding the data from the experiment?
A- Both objects always travel in the positive direction during the experiment.
B- Kinetic energy is conserved during the experiment.
C- The position of the center of mass of the system remains constant during the experiment.
D- The velocity of the center of mass of the two-object system remains constant during the experiment.
The position of the center of mass of the system remains constant during the experiment.
Conservation of linear momentumThe principle of conservation of linear momentum states that the total momentum of the system before after collision is always conserved for both elastic and inelastic collision.
[tex]m_1 u_1 + m_2 u_2 = m_1 v_1 + m_2 v_2\ \ (elastic)\\\\m_1 u_1 + m_2 u_2 = v(m_1 + m_2 ) \ (inelastic)[/tex]
Conservation of kinetic energyThe total kinetic energy of the system is conserved for perfectly elastic collision BUT not conserved for inelastic collision.
The center mass of the system
The center mass of the system is always constant.
Thus, the position of the center of mass of the system remains constant during the experiment.
Learn more about elastic and inelastic collision here: https://brainly.com/question/7694106
The rate of conduction heat transfer through a plane wall of dimensions , and , thermal conductivity , and temperatures and on the faces can be determined as
Answer:
Answer is explained in the explanation section below.
Explanation:
It can be determined by the use of Fourier's law of heat conduction.
Fourier's Law of Heat Conduction: States that, the rate of heat transfer is directly proportional to the temperature change from higher temperature to lower temperature. And it is directly proportional to the area perpendicular to the direction of the heat flow.
Through this statement, we can write the equation of the Fourier's law:
Q = Rate of Heat transfer.
A = Area
dT = Change in Temperature from Higher to Lower = T1 - T2, where T1 is assumed to be higher temperature.
dx = thickness of the wall, through which heat is transferring.
So,
Q is directly proportional to Area perpendicular to the direction of the heat flow.
So, we can write:
Q [tex]\alpha[/tex] A
And
Q is directly proportional to temperature change.
So, we can write
Q [tex]\alpha[/tex] dT/dx
So, in order to remove the proportionality sign, we need to introduce a constant, which is ( -K) here, Thermal conductivity material of the plane wall.
So,
Q = - K.A . dT/dx
or
Q = - K . (H.W) . (T1-T2)/L
where, H = height of the wall
W = width of the wall
L = length of the wall.
So, by using the above equation, we can definitely determine the rate of heat transfer through a plane -wall.
Note: for your ease, I have drawn a schematic of the plane-wall and attached in the attachment.
Which type of electromagnetic wave has the least energy?
O A. Ultraviolet
O B. Infrared
O C. Microwaves
O D. Radio
Help!
Answer:
The answer is radio waves
Mrs. Bontkowski watches Connor Ladone on the basketball court. Connor dribbles the ball from one end of the court to the other. With an initial speed of 0 m/s and final speed of 14 m/s, he accelerates at a rate of 2 m/s/s. How long does it take Connor to get from one end of the court to the other?
Answer:
1. A ball rolls down a ramp for 15 seconds. If the initial velocity of the ball was 0.8 m/sec and the final velocity was 7 m/sec, what was the acceleration of the ball?. Mrs. Bontkowski watches Connor Ladone on the basketball court. With an initial speed of 0 m/s and final speed of. 14 m/s, he accelerates at a rate of 2 m/s? If a Creature Cat's Ferrari, with an initial speed of 10 m/s, accelerates at a rate of 50 m/s/s.Mrs. Bontkowski watches Connor Ladone on the basketball court.
Explanation:
Hope this helps you!
How much work is required to lift 40 N 1.5 M
Answer: 200 joules I think.
Explanation:
The thermodynamic processes that occur in nature ____________. The thermodynamic processes that occur in nature ____________. convert thermal energy into mechanical energy lead to a more ordered state cannot be reversed do not conserve energy
Answer:
convert thermal energy into mechanical energy
Explanation:
Thermodynamics generally deals with the energy changes in chemical reactions and how its affect or its influence of energy on those changes. It is widely known to be a branch of physics. It deals mainly on heat transfer processes whereby energy in the form of heat is converted into work. It simply covers or the study of energy flow in the world as a whole and the flow relationship to work, heat, the different forms of energy, and entropy.
Thermodynamics is a branch of physics that deals with the study of energy and its transformations in systems, including the transfer of heat and work. The thermodynamic processes that occur in nature convert thermal energy into mechanical energy, lead to a more ordered state, and cannot be reversed.
These processes are governed by the laws of thermodynamics, which describe the behavior of energy in various systems. The conversion of thermal energy into mechanical energy occurs through processes such as combustion, where heat is generated and used to perform work.
Natural processes tend to increase the overall order or organization in a system, known as an increase in entropy. While energy can be converted and transferred, the total energy within a closed system remains constant due to the law of energy conservation.
Therefore, the thermodynamic processes that occur in nature convert thermal energy into mechanical energy, lead to a more ordered state, and cannot be reversed.
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The frequency of a tuning fork can be found by the method shown. A long tube open at both ends is submerged in a beaker of water, and the vibrating tuning fork is placed near the top of the tube. The length L of the air column is adjusted by moving the tube vertically. The sound waves generated by the fork are reinforced when the length of the air column corresponds to one of the resonant frequencies of the tube. The smallest value for L for which a peak occurs in sound intensity is 5 cm.a) What is the frequency of the tuning fork? The speed of sound in air is 345 m/s. Answer in units of Hz.b) What is the value of L for the second resonant position? Answer in units of cm.c)What is the value of L for the third resonant position? Answer in units of cm.
Answer:
a. 3.45 kHz b. 5 cm c. 7.5 cm
Explanation:
a. What is the frequency of the tuning fork?
For a tube open at both ends, the frequency, f = nv/2L. The smallest frequency at the smallest length of air column, L = 5 cm = 0.05 m is the fundamental frequency and there, n = 1 and v = speed of sound in air = 345 m/s.
So, f = v/2L
So, f = 345 m/s/(2 × 0.05 m)
= 345 m/s ÷ 0.1 m
= 3450 Hz
= 3.45 kHz
b. What is the value of L for the second resonant position?
The second resonant frequency is f' = 2f
= 2 × 3450 Hz
= 6900 Hz
Since f = nv/2L and f' = second resonant frequency when n = 2.
So, f' = 2v/2L
f' = v/L
L = v/f'
= 345 m/s ÷ 6900 Hz
= 0.05 m
= 5 cm
c. What is the value of L for the third resonant position?
The third resonant frequency is f" = 3f
= 3 × 3450 Hz
= 10350 Hz
Since f = nv/2L and f" = third resonant frequency when n = 3.
So, f" = 3v/2L
2f' = 3v/L
L = 3v/2f'
= 3 × 345 m/s ÷ (2 × 6900 Hz)
= 1035 m/s ÷ 13800 Hz
= 0.075 m
= 7.5 cm
a)The frequency of the tuning fork will be 3.45 kHz.
b) The value of L for the second resonant position will be 5 cm.
c) The value of L for the third resonant position will be 7.5 cm.
What is frequency?Frequency is defined as the number of repetitions of a wave occurring waves in 1 second.
The tuning fork's frequency for a tube with both ends open is;
f = nv/2L
f = 345 m/s/(2 × 0.05 m)
f= (345 m/s) / (0.1 m)
f= 3450 Hz
f= 3.45 kHz
f' = 2f is the second resonant frequency.
f'= 2 × 3450 Hz
f'= 6900 Hz
f = nv/2L
For n=2,
f' = 2v/2L
f' = v/L
The value of L for the second resonant position;
L = v/f'
L= 345 m/s ÷ 6900 Hz
L= 0.05 m
L= 5 cm
f' = 3f is the third resonant frequency.
f' = 3 × 3450 Hz
f'= 10350 Hz
f = nv/2L
For, n = 3.
f' = 3v/2L
2f' = 3v/L
The value of L for the third resonant position;
L = 3v/2f'
L=( 3 × 345 m/s)/(2 × 6900 Hz)
L= 1035 m/s / 13800 Hz
L= 0.075 m
L= 7.5 cm
Hence,The frequency of the tuning fork,value of L for the second resonant position and value of L for the third resonant position will be 3.45 kHz. 5 cm and 7.5 cm respectively.
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At a certain location, wind is blowing steadily at 10 m/s. Determine the mechanical energy of air per unit mass and the power generation potential of a wind turbine with 90-m-diameter (D) blades at that location. Take the air density to be 1.25 kg/m3. The mechanical energy of air per unit mass is .05 Numeric ResponseEdit Unavailable. .05 correct.kJ/kg. The power generation potential of the wind turbine is
Answer:
[tex]X=3976.078202kW \approx 3976kW[/tex]
Explanation:
From the question we are told that
Wind speed[tex]V_w=10m/s[/tex]
Turbine blade diameter [tex]D=90m[/tex]
Air density [tex]\tau=1.25kg/m^3[/tex]
Mechanical energy [tex]K.E =0.05kJ/kg[/tex]
Generally the power generation potential of the wind turbine X is mathematically given as
[tex]X=m'*K.E[/tex]
Where
[tex]m'=\tau *\pi*D^2/4*V[/tex]
[tex]m'=1.25 *\pi*90^2/4*10[/tex]
[tex]m'=79521.56404kg/s \approx 79521.5kg/s[/tex]
Therefore
[tex]X=m'*K.E[/tex]
[tex]X=79521.56404*0.05[/tex]
[tex]X=3976.078202kW \approx 3976kW[/tex]
[tex]X=4.0MW[/tex]
Suppose that the voltage is reduced by 10 percent (to 90 V). By what percentage is the power reduced
Answer:
percent decrease in power = 20 % .
Explanation:
Power P = v² / R where v is voltage and R is resistance which is constant .
taking log on both sides
log P = 2 log v - log R
differentiating on both sides
dP/P = 2 dv/v
-dP/P x 100 = 2 x -dv/v x 100
percent decrease in power = 2 x percent decrease in v ( voltage )
percent decrease in power = 2 x 10 = 20 %
What is the density of a cube that has a mass of 3.75 g and a volume of 3 mL?
Answer:
[tex]\displaystyle \rho=1.25\ g/ml[/tex]
Explanation:
Density
The density of a substance is the mass per unit volume. The density varies with temperature and pressure.
The formula to calculate the density of a substance of mass (m) and volume (V) is:
[tex]\displaystyle \rho=\frac{m}{V}[/tex]
The cube has a mass of m=3.75 g and a volume of V=3 ml, thus the density is:
[tex]\displaystyle \rho=\frac{3.75\ g}{3\ ml}[/tex]
[tex]\boxed{\displaystyle \rho=1.25\ g/ml}[/tex]
Since 1 kg=1000 mg and 1 lt = 1000 ml, the density has the same value but with different units:
[tex]\displaystyle \rho=1.25\ kg/l[/tex]
The view of light that describes light as consisting of particles is called: Select the correct answer below: particulate spherical discrete corpuscular
Answer: Corpuscular.
Explanation:
There is a theory called the Corpuscular Theory of Light, which says that light is made of small particles called "corpuscles".
But as we know, light has a duality associated to it (it behaves like a wave and like a particle), and here is where one of the largest problems of this theory appears, because it does not explain things like diffraction or interference.
Then the correct option is corpuscular.
Answer:
hes right
Explanation:
Planets A and B have the same size, but planet A is half the mass of planet B.
Which statement correctly explains the weight you would experience on each
planet?
O A. You would weigh the same on both planets because the planets
are the same size.
B. You would weigh less on planet A because it has less mass than
planet B.
C. You would weigh more on planet A because it has less mass than
planet B.
D. You would weigh the same on both planets because your mass
would be the same on both.
SUBMIT
Answer: Choice B) You would weigh less on planet A because it has less mass than planet B.
=====================================================
Explanation:
Weight is due to the force of gravity. The higher the force of gravity, the more pull and therefore the larger weight.
Imagine that gravity was basically a rope pulling a person down. The higher the force of gravity, the stronger the pull on the rope.
Due to planet A having less mass compared to planet B, this means the force of gravity on planet A is smaller, and therefore a person on planet A will weigh less compared to planet B.
-------------
As a more real world example, the moon's mass is less than the Earth's mass. It turns out that weights on the moon are roughly 1/6 of what they would be on Earth. This means that if a person weighed 180 pounds on Earth, then they would weigh about 180*(1/6) = 180/6 = 30 pounds on the moon. This is why astronauts on the moon are able to jump higher and have a bigger bounce in their step, even if they aren't even trying to jump so high.
A water bug is suspended on the surface of a pond by surface tension (water does not wet the legs). The bug has six leg, and each leg is in contact with the water over a length of 5 mm. What is the maximum mass (in grams) of the bug if it is to avoid sinking
Answer:
m = 2.2 x 10⁻⁴ kg = 0.22 g
Explanation:
The surface tension of water is 0.072 N/m. So in order for the bug to avoid sinking, its weight per unit length of contact must be no more than the surface tension of water. Therefore,
[tex]Weight\ of bug\ per\ unit\ length = Surface\ Tension\ of\ Water\\\frac{mg}{L} = Surface\ Tension\ of Water\\m = \frac{(Surface\ Tension\ of\ Water)(L)}{g}[/tex]
where,
m = mass of bug = ?
g = acceleration due to gravity = 9.81 m/s²
L = Contact length = (contact length of each leg)(No. of Legs) = (5 mm)(6)
L = 30 mm = 0.03 m
Therefore,
[tex]m = \frac{(0.072\ N/m)(0.03\ m)}{9.81\ m/s^{2}} \\[/tex]
m = 2.2 x 10⁻⁴ kg = 0.22 g
A 12-kg hammer strikes a nail at a velocity of and comes to rest in a time interval of 8.0 ms. (a) What is the impulse given to the nail
Answer:
Impulse = 0.9408Ns
Explanation:
Impulse is the product of force and time
Impulse = Ft
Given
Force F = mg
F = 12(9.8)
F = 117.6N
Time = 8 * 10^-3 = 0.008s
Get the impulse
Impulse = 117.6*0.008
Impulse = 0.9408Ns
What is the current theoretical explanation of how stars form
"The theory of low-mass star formation, which is well-supported by observation, suggests that low-mass stars form by the gravitational collapse of rotating density enhancements within molecular clouds."
Answer:
The current theoretical explanation of how stars form that they are formed by some type of gravitational collapse of rotating density enhancements within the molecular clouds.
Hope this helped!
P.S I used the notes my teacher gave me since we are learning about this.
Have a supercalifragilisticexpialidocious day!
What surprises you about ancient belief systems about the age of the universe?
True or false: There is only one possible choice of system which could be correct when doing problems using work and energy.
Answer:
the relationship is scalar, it is independent of the specific reference system
The statement is false
Explanation:
When the concepts of work and energy are being used, a reference system must be defined to perform the calculations,
in the case of work it is defined by the relation
W = F. d
where the point represents the scalar product, therefore the work is a scalar magnitude, it has only modulus for which any reference system is selected since the result is independent of the direction of the force, only the projection of the force depends in the given direction.
For the part of the energy it therefore has two main forms, kinetic energy and potential energy.
For kinetic energy the expression is
K = ½ m v²
therefore, the energizes only depends on the speed module and any reference system, since it will be selected
for gravitational and elastic power energy. It does not depend on the specific value at the point but on the difference with respect to an arbitrarily defined zero, therefore, as the difference is constant, it is independent of the reference system used.
In conclusion, since the relationship is scalar, it is independent of the specific reference system, so we can select several reference systems
Which type of electromagnetic radiation is useful in communications
technology?
ANSWER : RADIO WAVES
Explanation:
radio wave: Electromagnetic radiation having a wavelength between about.5 centimeters and 30,000 meters; used for the broadcasting of radio and television signals.
