Solar energy can be changed into thermal energy without any work being done. true or false

What is the period of a pendulum that is 1.3 m long?

Mkey [24]

Answer:

T≈2.2876585681s

Explanation:

Since you were not given the degrees of amplitude or radians of amplitude, we assume that the degrees of amplitude are less than 20∘ or 20∘ and we also assume that this is a simple pendulum

6 0

3 years ago

Which of these is caused by a chemical change?

dybincka [34]

<span>b.the skin of a banana turns from green to yellow as it ripens. </span>

4 0

3 years ago

An object is released from rest near a planet’s surface. A graph of the acceleration as a function of time for the object is sho

Natasha_Volkova [10]

Answer:

the body has descended a height (4a)

Explanation:

This exercise should use the acceleration given in the graph, but unfortunately the graph is not loaded, but we can build it, using the law of universal gravitation and the fact that you indicate that the movement is near the surface of the planet

F = m a

f

orce is gravitational force

G M m / r² = m a

a = G M / r²

where G is the universal constant of gravitation, M the mass planet and r the distance from the center of the planet of radius R to the body, if we measure the height of the body from the surface of the planet (y), we can write

r = R + y

for which

a = G M/R² (1+ y/R)⁻²

if we use y«R we can expand the function in series

a = (G M /R²) (1 -2 y/R - 2 (-2-1) /2! y² / R² +…)

as the height is small we can neglect the quadratic term and in many cases even the linear term, for this exercise we will remain only constant therefore the acceleration is constant

a = G M / R²

from this moment we can use the relations of motion with constant acceleration for the exercise

a) they ask us for the position for t = 2s

y = y₀ + v₀ t - a t²

as the body is released v₀ = 0

y-y₀ = - a t²

y-y₀ = - a 2²

y-y₀ = - a 4

therefore

therefore the body has descended a height (4a) where a is the acceleration of the planet's gravity

5 0

3 years ago

An electron in the n=7 level of the hydrogen atom relaxes to a lower energy level, emitting light of 1005 nm. Part A What is the

matrenka [14]

Answer:

rom level n = 7 to level n = 3

Explanation:

Bohr's model describes the energy levels for the hydrogen atom

En = -13.606 / n²

Where n is an integer with values of 1, 2, 3

An electronic transition occurs between two permitted levels of energy

ΔE = $E_{nf}$ - $E_{no}$

Let's apply these relationships our problem.

Let's start by knowing the energy of level n = 7

E₇ = - 13.606 / 7²

E₇ = - 0.27767 eV

Now let's see what the energy of the emitted photon

E = h f

c = λ f

f = c / λ

E = h c / λ

E = 6.63 10⁻³⁴ 3 10⁸/1005 10⁻⁹

E = 19,791 10⁻²⁰ J

Let's reduce to eV

E = 19,791 10⁻²⁰ (1 eV / 1.6 10⁻¹⁹)

E = 1,237 eV

The possible transitions from this level are towards n = 6, 5, 4,3,2, 1

We must test the different values until we find the right one

Energy of the states

n $E_{n}$

6 -0.378

5 -0.544

4 -0.850

3 -1,512

2 -3,402

1 -13,606

Let's examine the transition n = 7 to n = 6

ΔE = - 0.27767 - (-0.3779)

ΔE = 0.10023 eV

n = 7 to n = 5

ΔE = -0.27767 - (-0.5442)

ΔE = 0.267 eV

n = 7 a n = 4

ΔE = -0.27767- (-0.8504)

ΔE = 0.573 eV

n = 7 a n = 3

ΔE = -0.27767 - (- 1.5118)

ΔE = 1.234 Ev

This is the transition sought, so that the electron goes from level n = 7 to level n = 3

7 0

3 years ago

Find the time it would take a car going 25 meters per seconds,east, to travel 400 meters per seconds,east

nexus9112 [7]

400÷25= 16seconds is the answer

3 0

3 years ago