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3 years ago

Which statement is true of magnets?

Physics

2 answers:

jonny [76]3 years ago

8 0

The answer would be B. Earth is an electromagnet.

The Earth is a giant electromagnet. It's electromagnetic field is generated from the currents of electricity coming from molten metal flowing in the outer core of our Earth. The heat from the inner core causes convection and that is how electric current flows within Earth.

Kamila [148]3 years ago

6 0

Earth us an electromagnet (apex)

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A small rocket to gather weather data is launched straight up. Several seconds into the flight, its velocity is 140 m/s and it i

Free_Kalibri [48]

Explanation:

The force will be 98 N....

7 0

2 years ago

A mechanic uses a hydraulic car jack to lift the front end of a car to change the oil. The jack used exerts 8,915 N of force fro

Vaselesa [24]

Answer:

63.05 cm²

Explanation:

We use Pascals law to find the answer.

The law says that in an incomprehensible , non-viscous fluid the pressure applied will transmit through out the fluid without a change.

So, Pressure on larger piston = pressure on smaller piston.

$\frac{444}{3.14} = \frac{8915}{A}$

A ≅ 63.05 cm²

3 0

2 years ago

Photoelectric effect:

Lynna [10]

Answer:

A. K = 0.546 eV

B. cooper and iron will not emit electrons

Explanation:

A. This is a problem about photoelectric effect. Then you have the following equation:

$K=h\nu-\Phi=h\frac{c}{\lambda} -\Phi$ (1)

K: kinetic energy of the ejected electron

Ф: Work function of the metal = 2.48eV

h: Planck constant = 4.136*10^{-15} eV.s

λ: wavelength of light = 410nm - 750nm

c: speed of light = 3*10^8 m/s

As you can see in the equation (1), higher the wavelength, lower the kinetic energy. Then, the maximum kinetic energy is obtained with the lower wavelength (410nm). Thus, you replace the values of all variables :

$K=(4.136*10^{-15}eV)\frac{3*10^8m/s}{410*10^{-9}m}-2.48eV\\\\K=0.546eV$

B. First you calculate the energy of the photon with wavelengths of 410nm and 750nm

$E_1=(4.136*10^{-15}eV)\frac{3*10^{8}m/s}{410*10^{-9}m}=3.02eV\\\\E_2=(4.13610^{-15}eV)\frac{3*10^{8}m/s}{750*10^{-9}m}=1.6544eV$

You compare the energies E1 and E2 with the work functions of the metals and you can conclude:

sodium = 2.3eV < E1

cesium = 2.1 eV < E1

cooper = 4.7eV > E1 (this metal will not emit electrons)

iron = 4.5eV > E1 (this metal will not emit electrons)

5 0

3 years ago

A 8.00g sample of substance (substance, molar mass = 152.0 g/mol) was combusted in a bomb calorimeter with a heat capacity of 6.

aleksandrvk [35]

Answer:

ΔH°comb=-5899.5 kJ/mol

Explanation:

First, consider the energy balance:

$m_{c} *Cp*(T_{2}-T_{1})=-n_{s} *H_{c}$ Where $m_{c}$ is the calorimeter mass and $n_{s}$ is the number of moles of the samples; $H_{c}$ is the combustion enthalpy. The energy balance says that the energy that the reaction release is employed in rise the temperature of the calorimeter, which is designed to be adiabatic, so it is suppose that the total energy is employed rising the calorimeter temperature.