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2 years ago

5

A minimum temperature thermometer in a standard weather instrument shelter measures an overnight low temperature of 36 degrees F

ahrenheit. Explain why frost was observed on the ground beneath the shelter, even though the recorded minimum temperature was above the freezing point.

1 answer:

Rudiy272 years ago

5 0

Answer:

Explanation:

Even though the minimum temperature is more than the freezing point, Frost was observed on the ground because the ground will cool rapidly as cool air tends to move towards the ground, the temperature of the ground is lower than the atmosphere a few feet above it.

As the thermometer is kept some feet above the ground so ground temperature may be lower than the minimum recorded temperature.

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A roller coaster car drops a maximum vertical distance of 35.4 m. Determine the maximum speed of the car at the bottom of that d

marissa [1.9K]

Answer:

The maximum speed of the car at the bottom of that drop is 26.34 m/s.

Explanation:

Given that,

The maximum vertical distance covered by the roller coaster, h = 35.4 m

We need to find the maximum speed of the car at the bottom of that drop. It is a case of conservation of energy. The energy at bottom is equal to the energy at top such that :

$mgh=\dfrac{1}{2}mv^2$

$v=\sqrt{2gh}$

$v=\sqrt{2\times 9.8\times 35.4}$

v = 26.34 m/s

So, the maximum speed of the car at the bottom of that drop is 26.34 m/s. Hence, this is the required solution.

8 0

2 years ago

8.4-1 Consider a magnetic field probe consisting of a flat circular loop of wire with radius 10 cm. The probe’s terminals corres

Vlad1618 [11]

Answer:

B_o = 1.013μT

Explanation:

To find B_o you take into account the formula for the emf:

$\epsilon=-\frac{d\Phi_b}{dt}=-\frac{dBAcos\theta}{dt}=-Acos\theta\frac{dB}{dt}$

where you used that A (area of the loop) is constant, an also the angle between the direction of B and the normal to A.

By applying the derivative you obtain:

$\epsilon=-Acos\theta (2\pi f) B_ocos(2\pi f t+ \alpha)$

when the emf is maximum the angle between B and the normal to A is zero, that is, cosθ = 1 or -1. Furthermore the cos function is 1 or -1. Hence:

$\epsilon=2\pi fAB_o=2\pi (100*10^3Hz)(\pi (0.1m)^2)B_o=19739.20Hzm^2B_o\\\\B_o=\frac{20*10^{-3}V}{19739.20Hzm^2}=1.013*10^{-6}T=1.013\mu T$

hence, B_o = 1.013μT

6 0

2 years ago

A storage tank holds methane at 120 K, with a quality of 25 %, and it warms up by 5°C per hour due to a failure in the refrigera

lord [1]

One of the fundamental pillars to solve this problem is the use of thermodynamic tables to be able to find the values of the specific volume of saturated liquid and evaporation. We will be guided by the table B.7.1 'Saturated Methane' from which we will obtain the properties of this gas at the given temperature. Later considering the isobaric process we will calculate with that volume the properties in state two. Finally we will calculate the times through the differences of the temperatures and reasons of change of heat.

Table B.7.1: Saturated Methane

$T_1 = 120K$

$p_1 = 191.6kPa$

$v_f = 0.002439m^3/kg$

$v_{fg} = 0.30367 m^3/kg$

Calculate the specific volume of the methane at state 1

$v_1 = v_f+x_1v_{fg}$

$v_1 = 0.002439+ (0.25)(0.30367)$

$v_1 = 0.0783m^3/kg$

Assume the tank is rigid, specific volume remains constant

$v_2 = v_1$

$v_2 = 0.0783m^3/kg$

Now from the same table we can obtain the properties,

At $v_g = 0.0783m^3/kg$

$T_2 = 145K$

$p_2 = 823.7kPa$

We can calculate the time taken for the methane to become a single phase

$t = \frac{T_2-T_1}{\dot{T}}$

Here

$T_1 =$ Initial temperature of Methane

$\dot{T} =$ Warming rate

Replacing

$t = \frac{(145-273)-(120-273)}{5}$

$t = \frac{25}{5}$

$t = 5hr$

Therefore the time taken for the methane to become a single phase is 5hr

5 0

2 years ago

If you want to maximize the magnetic force on a current in a conductor, how should you orient the current relative to the magnet

tia_tia [17]

Answer:

Should place the current perpendicular to the magnetic field

Explanation:

The magnetic force exerted on a current-carrying wire is given by

$F=ILBsin \theta$

where

I is the current in the wire

L is the length of the wire

B is the magnetic field

$\theta$ is the angle between the direction of the wire and the magnetic field

As we see from the formula, the magnetic force is maximum when

$sin \theta=1$

which means

$\theta=90^{\circ}$

So, when the current in the wire and the magnetic field are perpendicular to each other.

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2 years ago

The graph below shows the sunspot number observed between 1750 and 2000. The graph shows sunspot number on the y axis and years

OlgaM077 [116]

1850 to 1900 because the slope would be 105. It says what is the greatest fall, so the upward slope of 120 wouldn't count.

3 0

2 years ago

Read 2 more answers