Answer:
vii. c
ix. a
x. d
Explanation:
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The maximum allowable resistance for an underwater cable is one hundredth of an ohm per
meter and the resistivity of copper is 1. 54 x 10-80m.
a) Calculate the smallest cross sectional area of copper cable that could be used.
The copper cable's smallest possible cross-sectional area is 1.54 x 10-6 square meters.
To calculate the smallest cross-sectional area of the copper cable, we can use the formula for resistance:
R = ρ(L/A),
where R is the resistance (in ohms), ρ is the resistivity of the material (in ohm meters), L is the length of the conductor (in meters), and A is the cross-sectional area (in square meters).
Given the maximum allowable resistance (R) is 0.01 ohms per meter (one-hundredth of an ohm per meter) and the resistivity of copper (ρ) is 1.54 x 10^-8 ohm meters. Let's calculate the smallest cross-sectional area (A) that can be used.
First, we'll rewrite the formula for A:
A = ρ(L/R).
Since R is given as ohms per meter, we can set L to 1 meter for simplicity, and the formula becomes:
A = ρ(1/R).
Now, we can plug in the given values:
A = (1.54 x 10^-8)/(0.01).
A = 1.54 x 10^-6 square meters.
So, the smallest cross-sectional area of the copper cable that could be used is 1.54 x 10^-6 square meters.
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After 2 s, Isabela was riding her bicycle at 3 m/s on a straight path. After 5 s, she was moving at 5. 4 m/s. What was her acceleration
Isabela's acceleration was [tex]0.8 m/s^2[/tex]. We can use the following formula to find the acceleration:
a = (vf - vi) / t
where
a is the acceleration,
vf is the final velocity,
vi is the initial velocity, and
t is the time interval.
Using the given values:
vi = 3 m/s
vf = 5.4 m/s
t = 5 s - 2 s
= 3 s
a = (5.4 m/s - 3 m/s) / 3 s
a = 0.8 [tex]m/s^2[/tex]
Therefore, Isabela's acceleration was 0.8 [tex]m/s^2[/tex].
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The 8-kg crank OA, with mass center at G and radius of gyration about O of 0. 22 m, is connected to the 12-kg uniform slender bar AB. A constant counterclockwise torque M is applied to OA so that when OA swings through the vertical position, the speed of B is 8 m/s. Determine the magnitude of the torque M and the angular velocity of OA when it reaches the vertical position
According to the question the angular velocity of OA when it reaches the vertical position is given by ω.
What is velocity?Velocity is a measure of the rate of change in the position of an object over time. It is a vector quantity, meaning it has both magnitude (or length) and direction. Velocity is the speed of an object in a given direction. It is calculated by dividing the distance traveled by the time taken to travel that distance.
Let ω be the angular velocity of OA when it reaches the vertical position.
The angular momentum of the system about the center of mass G is given by:
[tex]L_G = I_G \omega + M[/tex]
where [tex]I_G[/tex] is the moment of inertia of the crank OA about G.
The moment of inertia of the crank OA about G is given by:
[tex]I_G = m_oa r_o^2 + m_ab l^2[/tex]
where [tex]m_{oa[/tex] is the mass of the crank OA, l is the length of the uniform slender bar AB, and [tex]r_o[/tex] is the radius of gyration of the crank OA about O.
The angular momentum of the system about the center of mass G due to the 12-kg uniform slender bar AB is given by:
[tex]L_G = m_{ab} v l[/tex]
where v is the speed of point B when OA swings through the vertical position.
By equating the two angular momentum equations, we have:
[tex]m_oa r_o^2 \omega + M = m_{ab} v l[/tex]
Rearranging the above equation, we obtain:
[tex]M = m_oa r_o^2 \omega + m_ab v l[/tex]
Substituting known values, we get:
[tex]M = 8 kg \times (0.22 m)^2 \times \omega + 12 kg \times 8 m/s \times 1 m[/tex]
[tex]M = 1.76 kg m^2/s^2 \omega + 96 kg m/s^2[/tex]
Thus, the magnitude of the torque M is given by:
[tex]M = 1.76 kg m^2/s^2 \omega + 96 kg m/s^2[/tex]
The angular velocity of OA when it reaches the vertical position is given by:
[tex]\omega = (M - 96 kg m/s^2) / (1.76 kg m^2/s^2)[/tex]
Substituting the known value for M, we get:
[tex]\omega = (1.76 kg m^2/s^2 \omega + 96 kg m/s^2 - 96 kg m/s^2) / (1.76 kg m^2/s^2)\\\omega = 1.76 kg m^2/s^2 \omega / 1.76 kg m^2/s^2\\\omega = \omega[/tex]
Hence, the angular velocity of OA when it reaches the vertical position is given by ω.
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Assuming your skin temperature is 37. 2 C and the temperature of your surroundings is 23. 4C , determine the length of time required for you to radiate away the energy gained by eating a 335- C ice cream cone. Let the emissivity of your skin be 0. 915 and its area be 1. 27 m^2
T=___h
It would take approximately 4.4 hours for the person to radiate away the energy gained by eating the ice cream cone.
To calculate the time required for a person to radiate away the energy gained by eating an ice cream cone, we need to use the Stefan-Boltzmann law, which states that the rate of heat transfer from an object is proportional to the fourth power of its temperature and its surface area.
The formula is given as: Q/t = εσA([tex]T^{4}[/tex] - [tex]T0^{4}[/tex])
where Q is the heat energy gained by eating the ice cream, t is the time taken to radiate it away, ε is the emissivity of the skin, σ is the Stefan-Boltzmann constant, A is the surface area of the skin, T is the skin temperature, and T0 is the temperature of the surroundings.
Plugging in the given values, we get: 335,000 J/t = 0.915 x 5.67 x [tex]10^{-8}[/tex] x 1.27 x ([tex]373.2^{4}[/tex] - [tex]296.4^{4}[/tex])
Solving for t, we get t ≈ 4.4 hours.
Therefore, it would take approximately 4.4 hours for the person to radiate away the energy gained by eating the ice cream cone.
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What is the maximum speed of a point on the outside of the wheel 15 cm from the axle?.
The maximum speed of a point on the outside of the wheel 15 cm from the axle would depend on the rotational speed of the wheel.
To calculate the maximum speed, we need to know the angular velocity of the wheel, which is the rate at which it rotates. If we assume that the wheel is rotating at a constant angular velocity, we can use the formula v = rω, where v is the linear velocity of the point on the outside of the wheel, r is the radius of the wheel (15 cm in this case), and ω is the angular velocity of the wheel in radians per second.
So, if we know the angular velocity of the wheel, we can plug it into this formula and calculate the maximum speed of a point on the outside of the wheel 15 cm from the axle.
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Show that 1Kwh is equal to 3.6MJ of energy.
Answer:
3.6 MJ
Explanation:
1 kWh = 1 MJ
Remember that this is the same as the equation Power×time = Energy
Step 1: Convert kWh (kiloWatt×hour) to Ws (Watt×second)
1 kW = 1000 Watt
1 h = 60 min×60 sec = 3600 seconds
1000 W×3600s = 3600000 Joules
Divide 3600000 J by 10^6 to get 3.6 Mega Joules
A pile driver is raised to a height if 3. 0m. How high would another pile driver with twice the mass of the first have ti be raised in order to have the same amount of potential energy? Please draw the work out! (20 points!)
The second pile driver must be raised to a height of 1.5m.
Assume the mass of the first pile driver is m and its height is h. Therefore, the potential energy (PE) of the first pile driver is given by:
PE1 = m * g * h
where g is the acceleration due to gravity.
Now, let's find the potential energy of the second pile driver, which has twice the mass of the first pile driver. The mass of the second pile driver is 2m.
To have the same amount of potential energy as the first pile driver, the second pile driver must be raised to a certain height, let's call it h2.
Therefore, the potential energy (PE2) of the second pile driver is given by:
PE2 = (2m) * g * h2
Since we want the potential energy of both pile drivers to be equal, we can set up an equation:
PE1 = PE2
m * g * h = (2m) * g * h2
We can cancel out the mass and acceleration due to gravity:
h = 2 * h2
Now we can solve for h2:
h2 = h / 2
Plugging in the value of h as 3.0m, we have:
h2 = 3.0m / 2
h2 = 1.5m
Therefore, the second pile driver, with twice the mass of the first pile driver, must be raised to a height of 1.5m in order to have the same amount of potential energy.
Here's a visual representation of the work:
First pile driver:
Potential energy (PE1) = m * g * h
Second pile driver:
Potential energy (PE2) = (2m) * g * h2
Since PE1 = PE2, we have m * g * h = (2m) * g * h2
Cancelling out mass and acceleration due to gravity, we get h = 2 * h2
Solving for h2, we find h2 = h / 2
Plugging in the value of h, we have
h2 = 3.0m / 2
= 1.5m
Therefore, the second pile driver must be raised to a height of 1.5m.
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______ solar involve(s) using light and infrared energy from the Sun entering a space through glass windows with no moving parts and no use of electrical energy
Passive solar energy involves using natural processes to capture and distribute the Sun's energy.
This technique utilizes building design features, such as window placement and materials, to allow sunlight to enter the space and provide heating, lighting, and ventilation without any need for mechanical or electrical systems.
One example of passive solar design is the use of south-facing windows to capture sunlight during the winter, while shading devices prevent overheating during the summer.
By reducing the need for artificial heating and cooling, passive solar energy can reduce energy costs and environmental impact while providing a comfortable and sustainable living or working space.
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Which latitude receives the most direct rays of the sun year-round?.
The latitude that receives the most direct rays of the sun year-round is the equator, which has a latitude of 0 degrees.
Due to the Earth's axial tilt, the sun's rays strike the Earth at different angles at various latitudes throughout the year. Near the equator, the sun's rays are nearly perpendicular to the Earth's surface, resulting in a more direct and intense sunlight.
At the equator, the sun is positioned directly overhead at least once a year during the equinoxes (around March 21st and September 21st). This means that the equator receives the most direct and concentrated sunlight throughout the year compared to other latitudes.
As one moves away from the equator towards higher latitudes, the angle at which the sun's rays hit the Earth becomes progressively steeper, resulting in less direct and more diffuse sunlight. This is why regions closer to the poles experience more significant variations in daylight and seasonal changes in sunlight intensity.
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