Item 2 Sea stars, sea urchins, sand dollars, and brittle stars are all members of the same group. What is the common name of the group to which they all belong

Because the charges at rest are unable to produce a magnetic field, neither of the two stationary charges will do so.

There is no magnetic field created when a charge is stationary since there is no motion inside the charge. Thus, nothing except an electric field is created.

Charges that are at rest can also feel the electric force. Charges in motion can experience magnetic force. Therefore, the electric field must not be zero and the magnetic field may or may not be zero if a charged particle at rest experiences an electromagnetic force.

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Explanation:

Electrostatic is a force between two non-conductors

while

Friction oppose the relative motion between two surface or object.

The tension is the only force exerted horizontally to the car.And according to Newton's Law, F = ma = 1210kg * 1.20m/s = 1452N.So T =1452N.

It just seems slick, almost like touching ice but without the frigid sensation, according to my firsthand experience of both. Sorry, it's really nothing exceptional. Any surface would be sufficient if it had some lubrication oil on it.

In reality, there are no frictionless planes. If they did exist, items on them would almost certainly behave exactly as Galileo predicted if they did. Despite not existing, they are extremely valuable for designing things like engines, motors, roads, and even tow truck beds, to mention a few.

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The proposed size of 10 miles long and 5 miles in diameter for such a colony is quite large and would require significant technological advancements in terms of materials, and construction to be feasible.

In general, a spinning cylinder produces lift when its top and bottom are subjected to higher pressure and quicker velocities, respectively. The lifting force, it was said, is pointed perpendicular to the cylinder velocity.

If r is an object's radius, v is its linear speed and is its angular velocity in radians per unit of time, then v = r. This formula connects these three values so that we can always determine the third if we know the first two.

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The dinosaurs produced a net counterclockwise torque of 9,400Nm about the end of the branch that was attached to the tree. The length of the branch is 4.7m.

τ = Σr × F = rmg

where g is the acceleration caused by gravity, m is the mass, and r is the distance.

Torque has a direct relationship with -

1.the object's mass, in m

2. The mass's separation, r, from the location where the torque is being calculated.

Therefore, the torque will change whether we increase or reduce them.

Therefore, increasing mass will result in an increase in torque, but since we must retain the same torque, we must reduce mass's distance from the location of the torque.

As a result, the mass should be moved closer to the location of the torque.

Total Mass = (80 + 120)kg

= 200kg

Torque = 9400N

τ = Σr × F = rmg

τ = 200 × r × 10

9400 = 200 × r × 10

r = 9400 / 2000

r = 4.7m

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Radioactive element  which keeps on decaying over the time. Decay of radioactive element always comes under first order kinetics. Therefore the half life time of  radioactive substance is 2seconds.

Half life tells about the time at which the radioactive material decays to half of its initial concentration.

Mathematically,

half life time=0.693/  rate constant of the decay

The half life of a radioactive substance is the time taken for the activity to halve. Using the graph to calculate the half life of the radioactive isotope, we find that activity that is 3500 so, half of this activity is 17500 which is corresponding to time 2 seconds.

Therefore the half life time of  radioactive substance is 2seconds.

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The mass of planet is 3.886×10^25 kg. The radius of planet is 1. 2x10^7m.

Complete Resolution. If the acceleration caused by gravity on the surface of the earth is given by the formula g, then the acceleration caused by gravity on a planet with a mass half that of the earth and a radius equal to that of the earth is given by the formula g/2. Where G = 6.67 ×10^-11 N m2/kg2 (Newton's gravitational constant).

As a result, acceleration due to gravity (a) depends on the gravitational constant (G), the mass of the Earth (M), and the radius of the Earth (R), but not on the mass of the body (m).

Given:

Radius of planet (r) =  1. 2x10^7m

Acceleration due to gravity (g) = 18 m/s^2

The acceleration due to gravity at the surface of the planet is,

[tex]g=G\frac{M}{r^2}[/tex]

Where, G = Universal gravitational constant

[tex]G= 6.67*10^-11N.m^2/kg^2[/tex]

[tex]M=\frac{g*r^2}{G}[/tex]

[tex]M=\frac{18*(1.2*10^7)^2}{6.67*10^-11}[/tex]

M =3.886×10^25 kg

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In a transformer, energy is carried from the primary coil to the secondary coil by The magnetic field in the iron core.

What is transformer?

A Transformer is an electrical device used to increase or decrease the voltage provided to an electrical circuit. It is made up of two or more coils of wire wound around a common core. The coils are typically referred to as the primary and secondary winding. Electricity flowing in the primary winding creates a magnetic field, which in turn induces a voltage in the secondary winding. The ratio of primary to secondary winding determines the output voltage. Transformers are used extensively in the electricity distribution network, enabling the safe and efficient transmission of electricity over long distances.

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Since this car moves at 45 kilometers per hour, an option which describes if the given value is speed or velocity include the following: D. speed, because there is no specific direction.

In Science, speed can be defined as the distance covered by a physical object per unit of time. This ultimately implies that, speed is a scalar quantity because it has magnitude but no direction.

In Science, velocity can be defined as the distance covered by an object per unit of time in a specific direction. This ultimately implies that, velocity is a vector quantity because it has both magnitude and direction.

In this context, we can reasonably infer and logically deduce that a car that moves at 45 kilometers per hour describes speed rather than velocity, because there is no specific direction mentioned.

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Since no direction is specified, the correct answer is the last option which is speed, because there is no specific direction

Speed is a scalar quantity. That is, it has only magnitude but no direction. While velocity is a vector quantity. That is, it has both magnitude and direction.

If a car moves at 45 kilometers per hour, only the car magnitude is given but no direction.

The option that describes if the given value is speed or velocity is speed, because there is no specific direction

Therefore, the correct option is speed, because there is no specific direction.

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The current required by the electric heater which has the power of 15,000 W is 62.5 A

The power of the heater = 15,000 W

The voltage used by the heater = 240 V

The current required by the electric heater can be found using the formula,

              P = VI

where P is the power of the electric heater

          V is the voltage used by the electric heater

           I is the current required by the electric heater

Let us rearrange the above equation in order to get the current required by the heater is

              I = P/V

Let us substitute the known values in the above equation, we get

             I = 15,000 / 240

               = 62.5 A

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Answer:

The amount of work done is 45 J.

Explanation:

We know that the force applied is 15N. The amount of displacement experienced by the box is 3 metres along the floor.

Thus, F= 15N

D= 3 metres

The formula for calculating work done is W= F×D

Thus, W=15×3

W=45J

Thus, the amount of work done is 45J.

It is False that  Visual inspection of the brake drum friction surface is not required, only measure drum diameter.

No matter whether the vehicle is moving forward or backward, drum brakes produce uniform braking force. Drum brakes produce the same amount of braking force in both directions, which explains this. This kind is typically utilized for the passenger car's rear brakes.

Unusual brake pedal sensation is one of the first indications when drum brakes are damaged or failing. Excessive brake drum wear might result in vibrations that can be felt in the pedal. When you press the pedal, any trembling or pulsating brought on by worn drums will be audible.

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According to Coulomb's Law the observation of repulsion between two objects provides more conclusive evidence that an object is charged, as opposed to attraction.

What is Coulomb's Law?

Coulomb's Law is a fundamental principle in physics that describes the interaction between electrically charged objects. It states that the force of attraction or repulsion between two charged objects is directly proportional to the product of the charges and inversely proportional to the square of the distance between them.

Attraction or repulsion between two objects is one way to determine if an object is charged. The presence of an electric charge on an object can be determined by observing whether it experiences a force of attraction or repulsion when brought near another charged object.

Attraction or repulsion between two charged objects is a fundamental effect of electric charges. Opposite charges will experience a force of attraction towards each other, while like charges will experience a force of repulsion away from each other. This is known as Coulomb's Law.

Therefore, as per Coulomb's Law the observation of repulsion between two objects provides more conclusive evidence that an object is charged, as opposed to attraction.

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Answer:

kgm/s(-1)

Explanation:

the units of momentum will be the product of the units of mass and velocity. Mass is measured in kg and velocity in ms-1, therefore, the SI unit of momentum will be kgm/s(-1).

The electric field inside the wire is equal to 1.5 V/16 cm, or 0.09375 V/cm.

What is battery?

Battery is a device that stores energy and is capable of providing a current of electricity when connected to an electrical device. It typically consists of one or more electrochemical cells, which convert stored chemical energy into electrical energy.

The current density inside the wire is equal to 2.0 A/16 cm, or 0.125 A/cm.
The wire's diameter can be calculated using the formula I = πρd2/4,
where I is the current in the wire,
ρ is the resistivity of nichrome,
and d is the diameter of the wire.
Plugging in the values given,
we get 2.0 = π(1.1×10-6 Ω•m)d2/4, or d2 = 8.18×10-5 m.
Taking the square root of both sides, we get d = 0.028 m, or 2.8 mm.

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The potential energy of Nan suitcase of mass 14 kg is 54.88 J.

Potential energy is the energy of a body due to its position in the gravitational field.

To calculate the potential energy, we use the formula below

Formula:

Where:

From the question,

Given:

Substitute these values into equation 1

Hence, the potential energy is 54.88 J.

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The gravitational force here between spheres has an estimated magnitude of 1.67 10-9 N.

Any two bodies' gravitational attraction is exactly equal to the sum of their masses and divided by the square of their distance from one another.

Gravity, often known as the gravity force will bring any two bodies together. Although everything in the cosmos is attracted to one another, this attraction is usually too weak to just be felt since the things are so far apart. Gravity's attraction lessens as things are moved farther apart, but its influence sphere is boundless.

F=GMm/r^2

G=6.67 x 10^-11N kg^2/m^2

M=(15kg)

m=15 kg

r=(3.0m)^2

putting values we have

(6.67 x 10^-11N kg^2/m^2)(15kg)(15kg)/(3.0m)^2

1.67 x 10^-9N

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Answer:

Q = N e     total charge passing point

Q = 2.0E20 * 1.6E-19 coul = 32 coulombs

2)    I = Q / t = 32 C / 60 s = .53 amps

3)   R = V / i = 12 volts / .53 amps = 23 ohms

Assuming a 6 kg block is coupled to a spring with a 350 N/m spring constant, and that there is 0.5 m between the two blocks.

Use the formula

U=1/2kx2

U=1/23500.52

U=43.75 J

Utilizing the law of conservation of energy, KE = U - f.d, where f is the frictional force acting on

1/2 mv2 = 43.75 - mgd

1/2 ×6×v²= 43.75-0.3×6×9.8×0.5\s

v= √11.643

The "spring constant," denoted by the letter "k," is a figure that effectively indicates how "stiff" a spring is. A significant value of k indicates that more power is needed to extend it a given distance than would be necessary to stretch a less stiff spring the same distance.

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The heat energy of the substance option (A) -1700J is correct.

We are given that,

Heat of fusion of a substance = ΔHf = 42.5J/g

Mass of the substance = m= 40g

The latent heat of fusion is the quantity of heat required to transform one gramme of a substance from a solid to a liquid. But in this case, it's important to figure out how much heat is released as liquid copper solidifies. So, ΔHf = -42.5 J/g

Thus , we have to calculated here the heat energy of the substance by the formula,

q = m·ΔHf

Where, q is heat energy ,m is mass ΔHf is the heat of fusion of a substance,

q = m·ΔHf

q = -42.5 J/g× 40g

q = -1700J

Therefore , the heat energy of the substance would be option (A) -1700J

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You could do to make the magnetic disk rotate faster: regular usage of a disc defragmentation program.

A magnetic disk is a storage device that writes, rewrites, and accesses data using the magnetization process. It has a magnetic layer that retains data as tracks, spots, and sectors.

You could do to make the magnetic disk rotate faster:

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The percentage of the lost kinetic energy of the car, at the midpoint of the skid, is 50%.

In physics, work is the measurement of the energy used to move objects. When you are walking, you're using energy to move your body so the work done would be greater than zero.

According to work-energy theorem, work is equal to force times displacement (W = F · x).

A type of energy is kinetic energy, which is the energy of a moving object. If an object is at rest, its kinetic energy is zero. Kinetic energy is equal to one half of a mass times velocity squared (KE = 0.5 · m · v²).

When a car goes into a skid and comes to a gradual stop, at the midpoint of the skid the car has spend 50% its kinetic energy. This is simply because the velocity of the car at the midpoint of the skid is half the velocity of the car when the car starts going into a skid, assuming constant acceleration.

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Displacement is a vector quantity thus, having different directional component. The component of the given displacement to the north is 98.99 m.

The displacement is the measure of how long and in which direction an object is moved from the starting position. Displacement is a vector quantity thus, characterized by a magnitude and direction.

In physics, displacement is the product of velocity and time. The vertical component of the displacement = d sin θ

horizontal component = d cos θ.

The component to the north for a displacement of 140m with the angle of 45° is = 140 × sin 45 = 98.99 m.

Therefore, the north component of the displacement is about 99 m.

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The velocity of the other piece of the pinata which has a mass of 3.86 kg

is 0.67 m/s

The mass of the candy-filled pinata = 4.4 kg

The mass of the first piece of the pinata = 0.54 kg

The velocity of the first piece of the pinata = 4.8 m/s

The mass of the second piece = 3.86 kg

The velocity of the other piece can be found using the formula,

          mu = m₁v₁ + m₂v₂

where m is the mass of the pinata

           u is the velocity of the pinata at rest

           m₁,m₂ are the masses of the first and second pieces of pinata

           v₁,v₂ is the velocity of the two pieces

Let us substitute the known values in the above equation, we get

          4.4 x 0 = 0.54 x 4.8 + 3.86v₂

                       = 2.592 + 3.86v₂

            3.86v₂ = -2.592

                    v₂ = 2.592/3.86

                         = 0.67 m/s

Therefore, the velocity of the other piece is 0.67 m/s

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Answer: Natural selection, Genetic drift , Mutations and Gene flow

Explanation:  

Answer:

False

Explanation

Poaching, habitat loss and diseases are contributing to the death of animals there, example: Gorilla

Answer:

false

Explanation:

Answer: The amount of Torque produced is 7.2 Nm.

Explanation:

Given:

Force applied (F) to the end of a wrench = 60 Newton

Length of wrench = 0.12 meter

To find:

Quantity of Torque produced

Solution:

The quantity of Torque produced can be calculated from the following formula:

Ƭ = r F sin(θ)  

Where,

Ƭ = Torque, r = radius, F = Force,  (θ) =  angle between F and the lever arm  

In the given question,

r = 0.12,

F= 60,

(θ)= 900           {Since the force is applied at the end of a wrench, it must be perpendicular}

Torque (Ƭ) = 0.12* 60 * sin 900

               = 7.2 m                    {sin 900 = 1}

Hence, in the given situation, 7.2 Nm Torque will be produced.

The angle (in degrees) of the water surface with the horizontal is 14.3 degrees

The angle of the water surface with the horizontal can be determined using the concept of the accelerations of gravity and centripetal force. The acceleration of gravity acts in the downward direction, and the centripetal force acts in the opposite direction of the acceleration. In this case, the horizontal acceleration of the tank is 2.45 m/s^2, which acts in the opposite direction of the gravitational acceleration.

The angle of the water surface with the horizontal can be found by taking the tangent of the ratio of the centripetal acceleration to the gravitational acceleration.

tan(theta) = (centripetal acceleration) / (gravitational acceleration)

tan(theta) = (2.45 m/s^2) / (9.8 m/s^2) = 0.25

Theta = 14.3 degrees

So the angle of the water surface with the horizontal is 14.3 degrees.

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In the renal medulla, a countercurrent mechanism keeps things in balance. The solution flows concurrently in the same direction. The solution flows in the opposite direction of the countercurrent flow.

Cross-current flow here, the liquids move in the opposing directions through the two tubes. One end of a tube in a single tube starts to flow a solution with a concentration of 0%, while the other end in the same tube starts to flow a solution with a concentration of 100%.

The kidneys have two countercurrent processes. They are the vasa recta and the Henle loop. The nephron's Henle's loop is a U-shaped structure. The two limbs of the vessel's two blood streams move in the opposing directions, creating countercurrents.

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The Cessna Cardinal, a single-engine light plane, has a wing area of 16.2 m² and an aspect ratio of 7.31 with span efficiency factor of 0.62 then the induced drag when the total weight is 9800 N is 18.8 N.

Given that,

Wing area (A) = 16.2m²

Aspect ratio (r) = 7.31

Efficiency factor (e) = 0.62

Weight of plane (W) = 9800 N

Velocity of airplane (v) = 251 km/h = 251× 5/18 = 69.72 m/s

We know,

Dynamic pressure (p) = 1/2ρv²

where ρ is density of plane = 1.225

p = 1/2 × 1.225 × 69.72 × 69.72 = 2977.29 pa

Lift coefficient Cl = W/p × A = W/(1/2ρv²) A

where, A is the area of wing

Cl = 9800/2977.29 × 16.2 = 0.203

Induced drag coefficient (Cd) = Cl²/πer² = (0.203 × 0.203)/(π × 0.62 × 7.31 × 7.31) = 0.041/(104.08) = 0.39×10⁻³

Induced drag (d) = p × A × Cd = 2977.29 × 16.2 × 0.39 × 10⁻³ = 18.8 N.

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