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3 years ago

10

A book sits on a bookshelf without moving until a student picks it up. Which law best explains why the book remains at rest unti

l the student picks it up? (AKS 3a1 DOK 1) Newton's Second Law log Newton's Third Law Newton's Law of Universal Gravitation Newton's First Law

1 answer:

svetoff [14.1K]3 years ago

8 0

Answer:

Newtons first law

Explanation:

object in rest stays at rest

object in motion stays in motion

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The critical angle for a substance is measured at 53.7 degrees. light enters from air at 45.0 degrees. at what angle it will con

faust18 [17]

When light travels from a medium with greater refractive index $n_1$ to a medium with smaller refractive index $n_2$ , there exists an angle (called critical angle) above which the light is totally reflected, and the value of this angle is given by
$\theta_c = \arcsin ( \frac{n_2}{n_1} )$
In this problem, we know that the critical angle is $\theta_c = 53.7^{\circ}$ , so we can find the ratio between the refractive indices of the two mediums:
$\frac{n_2}{n_1} = \sin \theta_c = \sin 53.7^{\circ} =0.81$
and since the second medium is air (n=1.00), the refractive index of the first medium is
$n_1= \frac{n_2}{0.81}= \frac{1.00}{0.81}=1.23$

In the second part of the problem, we have light entering from air ( $n_i = 1.00$ ) at angle of incidence of $\theta_i = 45.0 ^{\circ}$ , into the second medium with $n_r = 1.23$ . By using Snell's law, we can find the angle of refraction of the light inside the medium:
$n_i \sin \theta_i = n_r \sin \theta_r$
$\sin \theta_r = \frac{n_i}{n_r} \sin \theta_i = \frac{1.00}{1.23} \sin 45^{\circ}=0.574$
$\theta_r = \arcsin(0.574)=35.1^{\circ}$

3 0

3 years ago

Two masses are joined by a mass less string. A 33-N force applied vertically to the upper mass gives the system a constant upwar

lisov135 [29]

Lower mass: 1.20 kg, upper mass: 1.28 kg

Explanation:

In order to solve the problem, we consider the forces acting on the upper mass only first.

The upper mass is acted upon three forces:

The applied force $F_a=33 N$ , upward
The weight of the mass itself, $m_u g$ , where $m_u$ is the upper mass and $g=9.8 m/s^2$ is the acceleration of gravity, downward
The tension in the string, $T=16 N$ , downward

Therefore, the equation of the forces for the upper mass is:

$F_a - m_u g - T = m_u a$

where

$a=3.5 m/s^2$ is the acceleration (upward)

Solving for $m_u$ ,

$m_u = \frac{F_a-T}{a+g}=\frac{33-16}{3.5+9.8}=1.28 kg$

Now we can find the lower mass by considering the forces acting on it:

The tension in the string, T = 16 N, upward
The weight of the mass itself, $m_L g$ , where $m_L$ is the lower mass, downward

So the equation of the forces is

$T-m_L g = m_L a$

And solving for the mass,

$m_L = \frac{T}{a+g}=\frac{16}{3.5+9.8}=1.20 kg$

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4 years ago

The height of an object dropped from the top of a 64-foot building is given by h(t)=-16t^2+64. How long will it take the object

mojhsa [17]

Answer:

1.86 s

Explanation:

Given the expression

h(t) = -16t²+ 64...................... Equation 1

Where h = height of the object, t = time it will take the object to hit the ground.

Given: h = 64 foot.

We have to concert from foot to meters

If 1 foot = 0.3048 meters

Then, 64 foot = 0.3048×64 = 19.51 meters.

We substitute the value of h into equation

119.51 = -16t²+64

-16t² = 199.51-64

-16t² = 55.51

t² = 55.51/-16

t² = 3.469

t = √3.469

t = 1.86 s.

Hence it will take the object 1.86 s to hit the ground.

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3 years ago

Chlorine exist in Nature as two Chlorine atoms covalently bonded together Why does this occur

Salsk061 [2.6K]

Answer:

It is one of the 7 diatomics

Explanation:

Br

I

N

Cl

H

O

F

^ these are the 7 diatomic molecules. Atoms of these elements exist as a molecule consisting of two covalently bonded atoms of the same element.

Simply put, for these elements, the diatomic state of the atom is much more stable than the unbound one.

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What are the layers of the Sun, starting from the center and moving outward?

meriva

Answer:

There are three main parts to the Sun's interior: the core, the radiative zone, and the convective zone. The core is at the center. It the hottest region, where the nuclear fusion reactions that power the Sun occur. Moving outward, next comes the radiative (or radiation) zone.

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