Why do magnetic lines of forces make a closed loop?

Correct answer choice is :

C) The freezing and melting temperatures of a substance are the same.

Explanation:

Fluids have a particular temperature at which they convert into solids, identified as their freezing point. In theory, the melting point of a solid should be the same as the freezing point of the liquid. In practice, small variations among these measures can be seen. The freezing point of a matter is the same as that substance's melting point. At this distinct temperature, the substance can exist as either a solid or a liquid. At temperatures below the freezing/ melting point, the substance is a solid.

Answer: The correct answer is "The freezing and melting temperatures of a substance are the same".

Explanation:

Freezing temperature: It is the temperature at which the liquid becomes the solid.

Melting temperature: It is the temperature at which the solid starts converted into liquid.

The freezing point of a substance is the same as the melting point of the substance. During melting and freezing of the substance, the temperature remains same as the energy is spent in changing the phase of the substance not in changing the temperature.

Latent heat is there. It is a hidden heat. It is required to change phase of the substance without showing temperature on thermometer.

Boiling temperature: It is the temperature at which liquid gets converted into vapors. At this temperature, vapor pressure of the liquid equals to the pressure surrounding the liquid.

Final answer:

The weight of the brass washer is 82.3 grams.

Explanation:

The weight of the brass washer can be calculated using its density and volume. The volume of the washer can be found by subtracting the volume of the hole from the volume of the outer cylinder. The formula for the volume of a cylinder is πr^2h, where r is the radius and h is the height.

Given that the outside diameter is 4.50 cm, the radius is half of that, which is 2.25 cm (or 0.0225 m). The height of the washer is 1.50 mm, which is 0.0015 m. Using these values, we can calculate the volume of the washer:

Volume = π(0.0225)^2(0.0015) = 9.5747 x 10^-6 m^3

Now, we can calculate the weight of the washer using its volume and density:

Weight = Volume x Density = 9.5747 x 10^-6 m^3 x 8599 kg/m^3 = 82.3 g

Final answer:

The weight of the brass washer on a laboratory balance would be 59.5 grams.

Explanation:

To find the weight of the brass washer, we need to calculate its volume and then multiply it by the density of brass. The volume of the washer can be found by subtracting the volume of the hole from the volume of the outside part of the washer.

The volume of the outside part of the washer can be calculated using the formula for the volume of a cylinder: V = π[tex]r^2[/tex]h. In this case, the radius (r) is half the outside diameter, so r = 4.50 cm / 2 = 2.25 cm = 0.0225 m. The height (h) is the thickness of the washer, which is 1.50 mm = 0.0015 m. Plugging these values into the formula gives us V = π(0.0225 [tex]m^2[/tex](0.0015 m) = 7.21 x [tex]10^{-6}[/tex] [tex]m^3[/tex].

The volume of the hole can also be found using the formula for the volume of a cylinder, since it is cylindrical in shape. The radius (r) of the hole is half the hole diameter, so r = 1.25 cm / 2 = 0.0125 m. The height (h) of the hole is the same as the thickness of the washer, which is 0.0015 m. Plugging these values into the formula gives us V = π(0.0125 [tex]m^2[/tex](0.0015 m) = 2.94 x [tex]10^{-7}[/tex] [tex]m^3[/tex].

Now, we can find the volume of the washer by subtracting the volume of the hole from the volume of the outside part: V_washer = 7.21 x [tex]10^{-6} m^3[/tex] - 2.94 x [tex]10^{-7} m^3[/tex] = 6.92 x [tex]10^{-6} m^3[/tex].

Finally, we can calculate the weight of the washer using the formula W = V_washer * density. Plugging in the values gives us W = 6.92 x [tex]10^{-6} m^3[/tex] * 8599 kg/[tex]m^3[/tex] = 5.95 x [tex]10^{-2}[/tex] kg = 59.5 g.

The magnitude of the skydiver's acceleration when the upward force of air resistance is half of his weight is 4.9 m/s² downward. This is found using Newton's Second Law and the skydiver's weight calculated from his mass and the acceleration due to gravity.

When the upward force of air resistance is equal to one-half of the skydiver's weight, the net force on the skydiver is only half of his weight acting downward. The skydiver's weight (W) can be calculated using the equation W = mg, where m is the mass and g is the acceleration due to gravity. For a mass (m) of 105 kg and assuming the acceleration due to gravity (g) is approximately 9.8 m/s2, the skydiver's weight would be 105 kg × 9.8 m/s2 = 1029 N. Half of this weight is 1029 N / 2 = 514.5 N.

According to Newton's Second Law (F = ma), the net force is equal to the mass multiplied by the acceleration. In this case, the net force is also the unbalanced force acting on the skydiver, which is half the skydiver's weight. Therefore, we have F = ma, which means 514.5 N = 105 kg × a. Solving for a, the acceleration, we get a = 514.5 N / 105 kg which is approximately 4.9 m/s2. Therefore, the magnitude of the skydiver's acceleration in this case is 4.9 m/s2 downward.

Answer:

If the racetrack’s length is 36 inches and is set to a height of 8 inches, 16 inches and 24 inches and each roll of the toy car is 7.8 seconds, 7.3 seconds and 6.6 seconds respectively, then, it only shows that the higher the racetrack, the faster the toy car will roll down because velocity, which measures how fast something is moving, is affected by gravity. Motion, as shown in this kind of scenario, is a kind of concept that depicts movement or change in position under given circumstances or factors over a period of time.

Explanation:

Answer:

C). W = 50 J

Explanation:

As we know that the work done is the product of force and displacement

so here it is given that the net force on the stack of books is 25 N

[tex]F = 25 N[/tex]

also the displacement of the stack of books is 2m as it is lifted upwards

so we have

[tex]d = 2 m[/tex]

now by the formula of work done we know

[tex]W = F.d[/tex]

now plug in all values in it

[tex]W = (25)(2)[/tex]

[tex]W = 50 J[/tex]

So,a)It will hit ground at 4.52seconds.b)At 145 ft/s fast is it going at the time of impact

An object is dropped from a 400-ft tower:

a) When does it hit the ground? Using the formula: time = [tex]\sqrt[1]{2*height/g}[/tex], where g is the acceleration due to gravity (32 ft/s²), the time taken to hit the ground is approximately 4.52 seconds.

b) How fast is it going at the time of impact? The velocity of the object when it hits the ground can be calculated as velocity = g * time, which gives a velocity of about 145 ft/s.

To find the speed of the bicycle, we can consider the gearing ratio between the sprocket assemblies and the wheel. The speed in feet per second can be calculated using the cyclist's pedalling rate and the circumference of the wheel. We can use conversion factors to convert the speed to miles per hour.

In order to find the speed of the bicycle, we need to consider the gearing ratio between the sprocket assemblies and the wheel. The ratio of the radii of the sprocket assemblies and the wheel can be used to determine the wheel's rotational speed.

Let's say the cyclist is pedaling at a rate of 1 revolution per second on the sprocket assembly with a radius of 4 inches. The sprocket assembly is connected to another sprocket assembly with a radius of 2 inches, which is then connected to the wheel with a radius of 14 inches.

The ratio of the radii between the sprocket assembly and the wheel is 14/2 = 7.

Therefore, the speed of the bicycle in feet per second can be calculated by multiplying the cyclist's pedalling rate by the circumference of the wheel:

Speed (feet per second) = 1 revolution/second x 2π x 14 inches = 28π inches/second = 28π/12 feet/second

To find the speed of the bicycle in miles per hour, we can convert the speed from feet per second to miles per hour:

1 mile = 5280 feet and 1 hour = 3600 seconds, so:

Speed (miles per hour) = (28π/12 feet/second) x (5280 feet/1 mile) x (1 hour/3600 seconds)

https://brainly.com/question/12574805

#SPJ12

Answer:

There are not enough neutrons to overcome the electrical repulsion of the protons.

Explanation:

Neutrons help stabilize a nucleus by attracting other nucleons (protons and neutrons). Although protons also attract other nucleons using the strong nuclear force, they repel other protons with the electrical force.

Hope this helps!

The backpack was lifted 1.25 meters high, and it weighed approximately 26.977 pounds.

To determine how high you lifted the backpack, we can use the formula for work done against gravity, which is W = F × h, where W is work (in joules), F is force (in newtons), and h is height (in meters). Since you did 150 joules of work to lift a 120-N backpack, we can rearrange the formula to solve for height (h): h = W / F = 150 J / 120 N = 1.25 meters. You lifted the backpack 1.25 meters high.

To find out how much the backpack weighed in pounds, we use the conversion factor that 1 newton is approximately equal to 0.224809 pounds. Therefore, 120 N × 0.224809 lb/N = 26.977 pounds. The backpack weighed approximately 26.977 pounds.

Answer:

B

Explanation:

Answer:

The object has larger mass. Examples would be like-cars of a different build driving at the same mph, or animals that typically run at the same speed but have different weights.

Explanation:

The more inertia that an object has, the more mass that it has.

Answer:

The efficiency of a screw is low because of friction.

Explanation:

A screw is a simple machine that is used to convert a torque to linear force and rotational motion to linear motion. The efficiency of a screw is given by :

[tex]\eta=\dfrac{Fl}{2\pi T}[/tex]

Where

l = pitch distance in mm

T = torque in N-m

The efficiency of screw is less because the output is less as compared to input or there is more input than output. This implies that there is more friction.

Hence, the correct option is (b) "friction".

Answer: option 4: circuit one will have more current.

Explanation:

Ohm's law states that the current in a circuit is proportional to voltage.

[tex]I \propto V \\ \Rightarrow I=\frac{V}{R}[/tex]

Let the current in the first circuit be I, voltage be V and resistance be R, the,

[tex]I_1=\frac{V_1}{R_1}[/tex]

The voltage in the second circuit is

[tex]V_2=\frac{V_1}{2}[/tex]

The resistance in the second circuit is:

[tex]R_2=2R_1[/tex]

[tex]\Rightarrow I_2=\frac{V_2}{R_2}=\frac{V_1/2}{2R_1}=\frac{I_1}{4}[/tex]

Hence, circuit one has 4 times more current than circuit two.

Answer:

Speed is the distance an object travels within a specific unit of time, whereas acceleration is the rate at which the speed or direction of an object is changing.

(Apex) Pretest

The option that best describes the difference between speed and acceleration is : ( B ) Speed is the distance an object travels within a specific unit of time, whereas acceleration is the rate at which the speed or direction of an object is changing.

Acceleration is the rate of change of velocity with time while speed is the rate of change distance with time.

Acceleration is a vector quantity because it has magnitude and direction while speed is a scalar quantity.

Hence we conclude that Speed is the distance an object travels within a specific unit of time, whereas acceleration is the rate at which the speed or direction of an object is changing.

Learn more about vector quantity  : https://brainly.com/question/356987

The hydraulic pressure on sample is [tex]3.35*10^{7} N/m^{2}[/tex].

Hydraulic pressure is the force imparted per unit area of a liquid on the surfaces which it has contact.

The magnitude of force acting on the small cylinder is equal to [tex]F_{N}[/tex].

In static equilibrium, all the torques should add up to zero:[tex]F_{N}l - 270(2l)= 0\\F_{N} = 270(2)\\F_{N} = 540 N[/tex]

The pressure applied to the fluid (through the small cylinder):

[tex]P= \frac{540}{\pi (\frac{2*10^{-2} }{2} )^2}[/tex]

[tex]P = 1.71*10^{6} Pa[/tex]

The force of fluid on the large cylinder:

[tex]F= P\pi R^{3} \\F= 1.71*10^{6} \pi (0.05^{2} )\\F= 1.34*10^{4} N[/tex]

The pressure on the sample:

[tex]P_{S} =\frac{F}{A} \\P_{S}= \frac{1.34*10^{4} }{4*10^{-4} } \\P_{S}= 3.35*10^{7} N/m^{2}[/tex]

To learn more about Hydraulic pressure here

https://brainly.com/question/857286

#SPJ2

The correct answer is

C. reduce the friction between its moving parts

In fact, by reducing the friction between the moving parts of the machine, it is possible to reduce the energy wasted due to this friction; therefore, more input energy is converted into useful work, and this will improve the efficiency of the machine.

Answer: We can reasonably improve a machines ability to do work by reducing the friction between the moving parts of machine. The correct answer is C.

Explanation:

According to the law of conservation of energy, the energy can neither be created nor destroyed. The energy can be converted from one form to another.

The energy is wasted due to the friction. It reduces the efficiency of the machines to do the work. There will be energy loss due to the friction. By reducing the friction, More energy can be converted into the work.

Therefore, we can reasonably improve a machines ability to do work by reducing the friction between the moving parts of machine.

The velocity of the toy car is 2m/s.

HOW TO CALCULATE VELOCITY:

Velocity (m/s) = Distance (m) ÷ time (s)

Velocity = 8m ÷ 4s

Velocity = 2m/s.

Learn more: https://brainly.com/question/20521883?referrer=searchResults

To find the range, maximum height, and speed at impact of a projectile fired with an initial speed of 500m/s and angle of elevation 30 degrees, we can use the equations of projectile motion.

To find the range, maximum height, and speed at impact of a projectile fired with an initial speed of 500m/s and angle of elevation 30 degrees, we can use the equations of projectile motion.

Range: The horizontal distance covered by the projectile is the range. In this case, we can use the formula:

R = (V02 * sin(2θ)) / g

where R is the range, V0 is the initial speed, θ is the angle of elevation, and g is the acceleration due to gravity.

Substituting the given values into the formula, we have:

R = (5002 * sin(2 * 30)) / 9.8

R = (250000 * sin(60)) / 9.8

R ≈ 1450.83 meters

Maximum Height: The maximum height reached by the projectile can be found using the formula:

H = (V02 * sin2(θ)) / (2 * g)

Substituting the given values into the formula:

H = (5002 * sin2(30)) / (2 * 9.8)

H ≈ 3060.45 meters

Speed at Impact: The speed at impact is the magnitude of the velocity of the projectile when it hits the ground. Since the projectile is fired at an angle and lands at a lower height than its initial position, the speed at impact will be lower than the initial speed. However, we need more information to calculate the exact speed at impact.

Answer: elastic potential energy

Explanation:

The form of energy stored in the string of the bow is elastic potential energy. Elastic potential energy is the energy stored in an elastic object (such as the string of a bow) when the object is compressed/stretched by a certain amount x with respect to its natural length. The elastic potential energy stored in the object is given by

[tex]U=\frac{1}{2}kx^2[/tex]

where k is the spring constant of the elastic string, and x is the compression/stretching.

The VW Beetle takes 25.53 seconds to reach a speed of 60.0 mi/h with an acceleration of 2.35 m/s². The top-fuel dragster has an acceleration of 22.36 m/s² to go from 0 to 30 mi/h in 0.600 seconds.

To calculate the time it takes for the VW Beetle to reach a speed of 60.0 mi/h, we need to use the equation v = u + at, where v is the final velocity, u is the initial velocity, a is the acceleration, and t is the time taken. Rearranging the equation to solve for t, we have t = (v - u) / a. Plugging in the values, we get t = (60.0 mi/h - 0) / 2.35 m/s² = 25.53 s.

To find the acceleration of the top-fuel dragster, we use the equation a = (v - u) / t, where a is the acceleration, v is the final velocity, u is the initial velocity, and t is the time taken. Rearranging the equation to solve for a, we have a = (v - u) / t. Plugging in the values, we get a = (30 mi/h - 0) / 0.600 s = 50 mi/h/s = 22.36 m/s².

https://brainly.com/question/12550364

#SPJ12

Answer:

The time is 0.428 hr.

Explanation:

Given that,

Final speed = 108 mph

Initial speed = 80 mph

Distance = 12 miles

We need to calculate the time

Using formula of time

[tex]v = \dfrac{d}{t}[/tex]

d = distance

t = time

Put the value into the formula

[tex]108-80=\dfrac{12}{t}[/tex]

[tex]t = \dfrac{12}{108-80}[/tex]

[tex]t =0.428\ hr[/tex]

Hence, The time is 0.428 hr.