The super keys of the relationship if a relation R(A, B, C, D) with four attributes A, B, C, and D is 8.
What is attribute?The quality of a feature is referred to as an attribute. The theory of attributes is concerned with the calculation of qualitative forms of qualities using quantitative measures. As a result, the characteristic requires slightly different types of statistical analyses than the variables do.
The given data,
Given three functional dependencies,
AB → C
BC → D
C → E
Finding the key of the relation, Compute closure of attribute,
{AB}⁺ = {A, B, C, D, E} {BC}⁺ = {B, C, D, E} {C}⁺ = {CE}
Only one candidate key is possible for a given relation = AB
Super keys of the relation = 2 (Total number of attributes in relations - Total number of attributes in each key).
Super keys of the relation = 2⁽⁵⁻²⁾
Super keys of the relation = 2³ = 8 keys
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A uniform 4.50 kg square solid wooden gate 1.50 m on each side hangs vertically from a frictionless pivot at its upper edge. A 1.20 kg raven flying horizontally at 4.50 m/s flies into this door at its center and bounces back at 1.50 m/s in the opposite direction. Part A What is the angular speed of the gate just after it is struck by the unfortunate raven
Answer:
A. 1.17
B.
the angular momentum is conserved because there is n o external force doing torque on the pivot
Linear momentum is not conserved because this is not an example of elastic collision where the final and initial kinetic energies are the same
Explanation:
A.
1.17 rad/s
B.
the angular momentum is conserved because there is n o external force doing torque on the pivot
Linear momentum is not conserved because this is not an example of elastic collision where the final and initial kinetic energies are the same
a man in a lift is moving upwards in a constant speed.the weight of the man is W.Acc
ording to Newtons third law,the reaction force of the weight W is the force of ?
Answer:
Normal force=mg
Explanation:
The reaction force of weight is the normal force.
in order to find the normal for we need to write all the forces and set it equal to the net force:
N-mg=ma (since it is a constant speed the a=0)
N=mg
Course hero N4M.6 A board has one end wedged under a rock having a mass of 380 kg and is supported by another rock that touches the bottom side of the board at a point 85 cm from the end under the rock. The board is 4.5 m long, has a mass of about 22 kg, and projects essentially horizontally out over a river. Is it safe for an adult with a mass of 62 kg to stand at the unsupported end of the board
Answer:
Therefore it is save to carry a 62kg adult
Explanation:
From the question we are told that:
Mass [tex]m=380kg[/tex]
Height of supporting Rock [tex]X=85cm[/tex]
Length of Board[tex]L_r=4.5m[/tex]
Mass of board [tex]M_b=22kg[/tex]
Mass of adult [tex]M_a=62[/tex]
Generally the moment of balance about wedge part about is mathematically given by
[tex]N -Q + R = Mg + mg[/tex]
[tex]0.85*N - Mg*2.25 - mg*(2.25 + x) = 0[/tex]
[tex]0.85*N = + Mg*2.25 + mg*(2.25 + x)[/tex]
where
[tex]N+R=4547[/tex]
therefore
[tex]N = 570.70588 + 1608.3529 + 714.823 x[/tex]
if N=0 at fallen person
[tex]x=3.04m[/tex]
Therefore it is save to carry a 62kg adult
Sometimes a person cannot clearly see objects close up or far away. To correct this type of vision, bifocals are often used. The top half of the lens is used to view distant objects and the bottom half of the lens is used to view objects close to the eye. Bifocal lenses are used to correct his vision. A diverging lens is used in the top part of the lens to allow the person to clearly see distant objects.
1. What power lens (in diopters) should be used in the top half of the lens to allow her to clearly see distant objects?
2. What power lens (in diopters) should be used in the bottom half of the lens to allow him to clearly see objects 25 cm away?
Answer:
1) P₁ = -2 D, 2) P₂ = 6 D
Explanation:
for this exercise in geometric optics let's use the equation of the constructor
[tex]\frac{1}{f} = \frac{1}{p} + \frac{1}{q}[/tex]
where f is the focal length, p and q are the distance to the object and the image, respectively
1) to see a distant object it must be at infinity (p = ∞)
[tex]\frac{1}{f_1} = \frac{1}{q}[/tex]
q = f₁
2) for an object located at p = 25 cm
[tex]\frac{1}{f_2} = \frac{1}{25} + \frac{1}{q}[/tex]
We can that in the two expressions we have the distance to the image, this is the distance where it can be seen clearly in general for a normal person is q = 50 cm
we substitute in the equations
1) f₁ = -50 cm
2)
[tex]\frac{1}{f_2} = \frac{1}{25} + \frac{1}{50}[/tex]
[tex]\frac{1}{f_2}[/tex] = 0.06
f₂ = 16.67 cm
the expression for the power of the lenses is
P = [tex]\frac{1}{f}[/tex]
where the focal length is in meters
1) P₁ = 1/0.50
P₁ = -2 D
2) P₂ = 1 /0.16667
P₂ = 6 D
In which direction does the magnetic field in the center of the coil point?
Answer:
Right
Explanation:
Coil move right yes
assuming weightless pulleys and 100% efficiency, what is the minimum input force required to lift a 120 N weight using a single fixed pulley?
A. 21 N
B. 61 N
C. 121 N
D. 241 N
Explain how grality and electric charge are different
An object A with mass 200 kg and an another object B with mass 1000 kg are moving with same speed. The ratio of kinetic energy of object A to B is
Answer:
Ratio of kinetic energy of object A to B = 1:5
Explanation:
Given:
Mass of object A = 200 kg
Mass of object B = 1,000 kg
Find:
Ratio of kinetic energy of object A to B
Computation:
Kinetic energy = (1/2)(m)(v²)
Kinetic energy of object A = (1/2)(200)(v²)
Kinetic energy of object A = (100)(v²)
Kinetic energy of object B = (1/2)(1,000)(v²)
Kinetic energy of object B = (500)(v²)
Ratio of kinetic energy of object A to B = Kinetic energy of object A / Kinetic energy of object B
Ratio of kinetic energy of object A to B = (100)(v²) / (500)(v²)
Ratio of kinetic energy of object A to B = 100 / 500
Ratio of kinetic energy of object A to B = 1/5
Ratio of kinetic energy of object A to B = 1:5
What is the Lorentz force law used for? A. To find the voltage of a battery B. To find the magnitude of a magnetic force C. To find the velocity of an electromagnetic wave. D. To find the direction of a magnetic field
Answer:
B
Explanation:
The Lorentz force is the sum of the electric force and magnetic force.
F = qE + qvB
qE represents electric force and qvB represents magnetic force
Which of the following is NOT part of the grain group?
Answer:
Any food made from wheat, rice, oats, cornmeal, barley, or another cereal grain is a grain product. Anything else is not
Explanation:
How much kinetic energy does an object have that is moving at a rate of 30 m/s and has a mass of 4000 kg ?
Answer:
K = 1800 kJ
Explanation:
Given that,
The speed of the object, v = 30 m/s
Mass of the object, m = 4000 kg
We need to find the kinetic energy of the object. The formula for the kinetic energy is given by :
[tex]K=\dfrac{1}{2}mv^2\\\\K=\dfrac{1}{2}\times 4000\times 30^2\\\\K=1800000\\\\or\\\\K=1800\ kJ[/tex]
So, the required kinetic energy is equal to 1800 kJ.
Guys can you please help me with this
2. What does SCA stand for? (1 Point) Student Conservation Association h Securities Class Action Sudden Cardiac Arrest Solar Cell Array:',)
Answer:
sudden cardiac arrest
Explanation:
Convert the following angles in degrees to radians:
(a) 300°
(b) 18°
(c) 105°
Answer:
a) 5.23599
b) 0.314159
c) 1.8326
Explanation:
Answer:
a. 5.236 rad
b. 0.314 rad
c. 1.833 rad
Explanation:
300° × π/180 = 5.236rad
18° × π/180 = 0.3142rad
105° × π/180 = 1.833rad
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
We say that the mass comes to rest if, after a certain time, the position of the mass remains within an arbitrary small distance from the equilibrium position. Will the mass ever come to rest
Answer:
No, the mass will never come to rest
Explanation:
It is so because even at arbitrarily small distance it will experience some amount of force (irrespective of how small the value of force is).
This does not allow the mass to become stationary or in a equilibrium state as it is still subject to some amount of force.
Hence, the the mass will never come to rest
please helppp:((( PLEASEEEEE
Answer:
is the amount of matter in this object
A 2.50 MHz sound wave travels through a pregnant woman's abdomen and is reflected from the fetal heart wall of her unborn baby. The heart wall is moving toward the sound receiver as the heart beats. The reflected sound is then mixed with the transmitted sound, and 78 beats per second are detected. The speed of sound in body tissue is 1500 m/s. Part A Calculate the speed of the fetal heart wall at the instant this measurement is made.
Answer:
the speed of the fetal heart wall at the instant is 0.0325 m/s
Explanation:
Given the data in the question;
f₀ = 2.50 MHz = 1.80 × 10⁶ Hz
f[tex]_B[/tex] = 78 beat per sec ( Hz )
V = 1500 m/s
the speed of the fetal heart wall at the instant this measurement is made = ?
now, if v is the magnitude of hart wall speed, V is speed of sound and f[tex]_h[/tex] the frequency the heart receives( and reflects), f₀ is original frequency and f, is reflected back;
so
heart is moving observer and device is stationary source
f[tex]_h[/tex] = ((V + v)/v )f₀
Heart is moving source and device is stationary observer
f' = (V/(V-v ))f[tex]_h[/tex]
Beats
f[tex]_B[/tex] = f₀ - f' = f₀ - f₀( V+v / V-v ) = f₀( 2v / V-v )
so we solve for v
v = V( f[tex]_B[/tex] / ( 2f₀ + f[tex]_B[/tex] )
so we substitute
v = 1500 ( 78 / ( (2×1.80 × 10⁶) + 78 )
v = 1500 ( 78 / ( 3,600,000 + 78 )
v = 1500 ( 78 / 3,600,078 )
v = 1500 ( 2.1666 × 10⁻⁵ )
v = 0.0325 m/s
Therefore, the speed of the fetal heart wall at the instant is 0.0325 m/s
The plates of a capacitor are charged using a battery, and they produce an electric field across the separation distance d between them. The two plates are now to be pushed together to a separation of d/2. The pushing together can be done either with the battery connected or with it disconnected. In which case, with the battery connected or disconnected. Is the electric field magnitude greater with the battery connected with the battery disconnected?
Answer:
Explanation:
The equation of the capacitance of the capacitor can be represented as:
[tex]C = \dfrac{\varepsilon_oA}{d}[/tex]
Also, the electric field between the plates can be expressed as:
[tex]E = \dfrac{\sigma}{\varepsilon_o}[/tex]
[tex]= \dfrac{Q}{A \varepsilon _o} \ \ (surface \ charge\ density \ \sigma =\dfrac{Q}{\varepsilon_o})[/tex]
However;
when pushed to a distance d/2, the new capacitance of the capacitor is:
[tex]C = \dfrac{\varepsilon _oA}{(d/2))}[/tex]
[tex]=\dfrac{2 \varepsilon_oA}{d}[/tex]
[tex]=2C \\ \\ Q' = CV \\ \\ = 2CV \\ \\ =2Q[/tex]
SImilarly, the new electric field between the plates is:
[tex]E' = \dfrac{\sigma'}{\varepsilon_o} \\ \\ = \dfrac{Q'}{A \varepsilon_o} \\ \\ = \dfrac{2Q}{A \varepsilon_o} \\ \\ =2E[/tex]
For Battery disconnected:
The electric field between the plates doesn't rely upon the distance between the plates yet relies upon the magnitude of the charge. At the point when the battery is detached, the charge on the capacitor stays as before, so does the electric field.
Therefore, the magnitude of the electric field when the battery is associated is twice however much the magnitude of the electric field when the battery is separated and disconnected.
Hence, the ratio is :
[tex]\dfrac{E_{connected}}{E_{disconnected}} =\dfrac{2E}{E} \\ \\ \dfrac{E_{connected}}{E_{disconnected}} = 2[/tex]
Hence, the ratio is = 2
calculate power disspated by the element of an electric fire (heater) of resistance 30 ohms when a
current of 10 amps flows in it. if is on for 30 hours in a week determine the energy used. determine the weekly cost of energy if eletricity costs K 13 per unit
Answer:
Weekly cost = K 8,190
Explanation:
Given the following data;
Resistance, R = 30 Ohms
Current, I = 10 Amps
Time, t = 30 hours
Cost = K13
I. To find the power dissipated;
Power = current² * resistance
Power = 10² * 30
Power = 100 * 30
Power = 3000 Watts
II. To find the energy consumption;
Energy = power * time
Energy = 3000 * 30
Energy = 90,000 Watt-hour = 90 KWh (1 Kilowatts is equal to 1000 watts).
III. To find the weekly cost;
Daily cost = Energy consumption * cost
Daily cost = 90 * 13
Daily cost = K 1170
Therefore, weekly cost = 1170 * 7
Weekly cost = K 8,190
During the spin cycle of a washing machine, the clothes stick to the outer wall of the barrel as it spins at a rate as high as 1800 revolutions per minute. The radius of the barrel is 26cm.
a. Determine the speed (in m/s) of the clothes which are located on the wall of the spin barrel.
b. Determine the acceleration of the clothes.
To answer the two questions, we need to know two important equations involving centripetal movement:
v = ωr (ω represents angular velocity in radians)
a = [tex]\frac{v^{2}}{r}[/tex]
Let's apply the first equation to question a:
v = ωr
v = ((1800*2π) / 60) * 0.26
Wait. 2π? 0.26? 60? Let's break down why these numbers are written differently. In order to use the equation v = ωr, it is important that the units of ω is in radians. Since one revolution is equivalent to 2π radians, we can easily do the conversion from revolutions to radians by multiplying it by 2π. As for 0.26, note that the question asks for the units to be m/s. Since we need meters, we simply convert 26 cm, our radius, into meters. The revolutions is also given in revs/min, and we need to convert it into revs/sec so that we can get our final units correct. As a result, we divide the rate by 60 to convert minutes into seconds.
Back to the equation:
v = ((1800*2π)/60) * 0.26
v = (1800*2(3.14)/60) * 0.26
v = (11304/60) * 0.26
v = 188.4 * 0.26
v = 48.984
v = 49 (m/s)
Now that we know the linear velocity, we can find the centripetal acceleration:
a = [tex]\frac{v^{2}}{r}[/tex]
a = [tex]\frac{49^{2}}{0.26}[/tex]
a = 9234.6 (m/[tex]s^{2}[/tex])
Wow! That's fast!
We now have our answers for a and b:
a. 49 (m/s)
b. 9.2 * [tex]10^{3}[/tex] (m/[tex]s^{2}[/tex])
If you have any questions on how I got to these answers, just ask!
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The function s(t)=−t3+3t+3 gives the distance from a starting point at time t of a particle moving along a line. Find the velocity and acceleration functions. Then find the velocity and acceleration at t=0 and t=1. Assume that time is measured in seconds and distance is measured in centimeters. Velocity will be in centimeters per second (cm/sec) and acceleration in centimeters per second per second (cm/sec2).
Answer:
v(t)=3t²+3, and a(t)=6t
v(0)=3cm/sec, and a(0)=0cm/sec²
v(1)=6cm/sec, and a(1)=6cm/sec²
Explanation:
Find velocity and acceleration functions ( v(t) and a(t) )
(Relevant background: Let's say f(t) is a function of y with respect to x. Think of the derivative of this function, f'(t) , as representing the rate at which y changes with respect to x)
s(t) is a function of distance with respect to time. Therefore, s'(t) - the derivative of this - represents the rate at which distance changes with time, which is just the definition of velocity. So we can say velocity v(t) = s'(t).
s(t)=t³+3t+3
s'(t)=v(t)=3t²+3
Similarly, if v(t) is a function of speed with respect to time, then v'(t) represents the rate at which speed changes with time, which is acceleration. So we can say that acceleration a(t)=v'(t)=s''(t)
v(t)=3t²+3
v'(t)=a(t)=6t
Find velocity and acceleration at t=0 and t=1
t=0
v(t)=3t²+3
v(0)=3(0²)+3
v(0)=3 cm/sec
a(t)=6t
a(0)=6(0)
a(0)=0 cm/sec²
t=1
v(t)=3t²+3
v(1)=3(1²)+3
v(1)=3+3
v(t)=6 cm/sec
a(t)=6t
a(1)=6(1)
a(1)=6 cm/sec²
The function s(t)=−t3+3t+3 gives the distance from a starting point at time t of a particle moving along a line.
v(t)=3t²+3, and a(t)=6t
v(0)=3cm/sec, and a(0)=0cm/sec²
v(1)=6cm/sec, and a(1)=6cm/sec²
What is velocity and acceleration functions ( v(t) and a(t)?Relevant background: Let's say f(t) is a function of y with respect to x. Think of the derivative of this function, f'(t) , as representing the rate at which y changes with respect to x.
s(t) is a function of distance with respect to time. Therefore, s'(t) - the derivative of this - represents the rate at which distance changes with time, which is just the definition of velocity. So we can say velocity v(t) = s'(t).
s(t)=t³+3t+3
s'(t)=v(t)=3t²+3
Similarly, if v(t) is a function of speed with respect to time, then v'(t) represents the rate at which speed changes with time, which is acceleration. So we can say that acceleration a(t)=v'(t)=s''(t)
v(t)=3t²+3
v'(t)=a(t)=6t
Find velocity and acceleration at t=0 and t=1
t=0
v(t)=3t²+3
v(0)=3(0²)+3
v(0)=3 cm/sec
a(t)=6t
a(0)=6(0)
a(0)=0 cm/sec²
t=1
v(t)=3t²+3
v(1)=3(1²)+3
v(1)=3+3
v(t)=6 cm/sec
a(t)=6t
a(1)=6(1)
a(1)=6 cm/sec²
Therefore, The function s(t)=−t3+3t+3 gives the distance from a starting point at time t of a particle moving along a line.
v(t)=3t²+3, and a(t)=6t
v(0)=3cm/sec, and a(0)=0cm/sec²
v(1)=6cm/sec, and a(1)=6cm/sec²
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The sensor on a door for a home security system consisted of a small coil of wire
embedded in the doorframe, and a small steel disk on the door opposite the coil.
When the door was opened, what characteristic of the coil changed for the home
security system?
Answer:
Probably electromagnetism
Explanation:
When the door is closed, the steel disk on the door is in close proximity to the coil of wire in the doorframe. This creates a magnetic field around the coil, which induces a small current in the coil.
What is the magnetic field?Ampere's law, which says that the magnetic field created by a current-carrying wire is proportional to the current and inversely proportional to the distance from the wire, may be used to describe the magnetic field produced by a long straight wire carrying a current.
When the door is opened, the steel disk moves away from the coil, which causes the magnetic field to weaken. As a result, the current induced in the coil decreases. This change in current is detected by the home security system as a change in the magnetic field and is interpreted as the door being opened.
In other words, the characteristic of the coil that changes when the door is opened is the amount of current induced in it. The decrease in the magnetic field as the steel disk moves away from the coil results in a decrease in the induced current, which signals to the home security system that the door has been opened.
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Which lists the springs in order of increasing spring constant?
W, Y, X, Z
OW, Y, Z, X
O Z, X, Y, W
OX,Z,Y, W
Answer:
is there supposed to be a picture?
Explanation:
The correct order of the springs in increasing spring constant is: W, Y, X, Z. The correct option is A.
What is the spring constant?Spring constant, also known as force constant or stiffness, is a measure of the resistance of a spring to deformation when a force is applied to it. It is defined as the amount of force required to stretch or compress a spring by a given distance.
The formula for the spring constant is:
k = F/x
Where
k = is the spring constant,
F = is the applied force,
x =is the displacement or deformation of the spring.
The unit of spring constant is newtons per meter (N/m) in the SI system of units, or pounds per inch (lb/in) in the Imperial system.
A higher spring constant means that a spring is stiffer and requires more force to be stretched or compressed by a given distance. A lower spring constant means that a spring is more flexible and requires less force to be stretched or compressed by a given distance. The spring constant is an important property of springs, which are used in various applications, such as in suspension systems, mattresses, and mechanical watches.
Here in the Question,
In order to determine the order of increasing spring constant, we need to compare the given springs and see which one requires more force to stretch or compress.
Therefore, The correct order of the springs in increasing spring constant is: W, Y, X, Z. This is because the spring constant increases as we move from W to Z.
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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
how to measure the weight of an object?? PLEASE HELP I'LL GIVE BRAINLEST
Answer:
Weight is a measure of the force of gravity pulling down on an object. It depends on the object's mass and the acceleration due to gravity, which is 9.8 m/s2 on Earth. The formula for calculating weight is F = m × 9.8 m/s2, where F is the object's weight in Newtons (N) and m is the object's mass in kilograms.
I will mark you brainlist! Use your own word
What is the weathering, erosion, and deposition?
Weathering is the breaking down or dissolving of rocks and minerals on Earths surface.
Erosion is the process by which the surface of the Earth gets worn down. Erosion can be caused by natural elements such as wind and glacial ice
Deposition is the dropping of sediment by wind, water, ice, or gravity.
Answer:
Weathering: refers to the process of breaking down and disintegrating rocks, minerals, soils, as well as several other materials.
Erosion: refers to the process of wearing down the surface of the earth due to glacial ice, wind and other natural elements.
Deposition: refers to the geological process, of sediments and soil, added to landforms due to wind, ice and other natural elements to build up layers od sediments.
Explanation:
List two types of current
Answer:
static and current electricity
create a poem that incorporates those ten words. Feel free to make it as silly as you like! MINIMUM of 6 lines with a MINIMUM of 5 words and 10 should come from your book. These do not have to rhyme, but can if you wish.
I could make a poem for you if you actually gave the words...... what 10 words do i need to incorporate???☹︎
Which of the following would be most likely to contribute to molecules
experiencing intermolecular forces?
O A. Containing oxygen
B. Containing charged regions
O C. Electric neutrality
O D. Being made of atoms
Answer:
B. Containing charged regions
Explanation:
The term i.e. intermolecular forces would be used to explain the attraction forces. Here the interaction would be done between molecules etc that acts between the acts & the other types of particles i.e. neighboring like atoms or ions
So in the given case, the option b would be contributed to the molecules that have intermolecular forces
hence, the option b is correct