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3 years ago

A 3kW oven supplied with 9kJ of energy. How many seconds can it be run for

1 answer:

4 0

The energy consumption rate of the oven is
3 kW = 3000 W = 3000 J/s.

The amount of energy supplied is
9 kJ = 9000 J

The time that the oven will run is
$t= \frac{9000 \, J}{3000 \, J/s} = 3 \, s$
(9000 J)/(3000 J/s) = 3 s

Answer: 3 seconds

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Violet light of wavelength 427 nm ejects electrons with a maximum kinetic energy of 0.684 eV from a certain metal. What is the w

frutty [35]

Answer:

The work function of the metal is 2.226 eV.

Explanation:

Given;

wavelength of the violet light, λ = 427 nm = 427 x 10⁻⁹ m

maximum kinetic energy, K.E = 0.684 eV

The energy of the incident light is calculated as;

$E = hf = \frac{hc}{\lambda} = \frac{6.626 \ \times \ 10^{-34} \ \times\ 3\ \times \ 10^8 }{427 \ \times \ 10^{-9}} = 4.655 \ \times \ 10^{-19} \ J\\\\1 \ eV = 1.6 \ \times \ 10^{-19} \ J\\\\E =( \frac{4.655 \ \times \ 10^{-19} \ J }{1.6 \ \times \ 10^{-19} \ J} ) \ eV\\\\E = 2.91 \ eV$

Apply Einstein's photoelectric equation;

E = Ф + K.E

where;

Ф is the work function of the metal

Ф = E - K.E

Ф = 2.91 eV - 0.684 eV

Ф = 2.226 eV.

Therefore, the work function of the metal is 2.226 eV.

5 0

3 years ago

Need amswer fast plz

FrozenT [24]

Answer:

I need this for may schooling

6 0

2 years ago

The trachea splits into two branches called larynx true or false<br> pls answer somebodyyyyyyy

kirill115 [55]

Answer:

False

Explanation:

The trachea divides into left and right air tubes called bronchi, which connect to the lungs. Within the lungs, the bronchi branch into smaller bronchi and even smaller tubes called bronchioles.

Hope this helps :)

7 0

3 years ago

A rock is thrown upward from the level ground in such a way that the maximum height of its flight is equal to its horizontal ran

marshall27 [118]

Answer

a) For the rock

$\dfrac{v_t^2sin 2\theta}{g} = \dfrac{v_t^2sin^2\theta}{2g}$

$2sin\thetacos\theta = \dfrac{sin^2\theta}{2}$

$2cos\theta = \dfrac{sin\theta}{2}$

$tan\theta = 4$

$\theta = tan^{-1} 4$

$\theta = 76^0$

b) $\theta = 45^0$ for maximum range

$\dfrac{d_{max}}{d}=\dfrac{(v_tcos 45^0)(2v_tsin 45^0)g}{(v_tcos 76^0)(2v_tsin 76^0)g}$

$\dfrac{d_{max}}{d}=\dfrac{0.707\times 0.707)}{0.97\times 0.242}$

$\dfrac{d_{max}}{d}=2.129$

$d_{max}=2.129 d$

c) The value of θ is the same on every planet as g divides out.

5 0

3 years ago

Please help im on a timer!! 50 points!!

Crank

Strength of the magnetic field: C) 20 T

Explanation:

When a conductive wire moves in a region with magnetic field, an electromotive force is induced in the wire due to the phenomenon of electromagnetic induction.

If the wire moves perpendicular to the field, the magnitude of the induced emf in the wire is given by

$\epsilon=BLv$