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salantis [7]
3 years ago
8

A book is dropped from a window. It takes 5 seconds to reach the ground. What is its velocity after 2 seconds? What’s the veloci

ty at the time when it hits the ground?
Physics
1 answer:
ira [324]3 years ago
3 0

Answer:

Explanation:

Initial velocity is 0. In the equation v = v0+at where v0 is the initial velocity of 0, we only have to fill in -9.8 for a and 2 for t to get the velocity after 2 seconds -19.6 m/s; after 5 seconds, when it hits the ground, a = -9.8 and t = 5 to give a velocity of -49 m/s. Gravity pulls down everything at the same rate, it doesn't matter whether we drop a feather or an elephant from the window!

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A ray is incident on a film of thickness t and the index of refraction n=1.6 at an angle θ = 35 degrees. Find the angle of refra
lidiya [134]

Answer

Given,

refractive index of film, n = 1.6

refractive index of air, n' = 1

angle of incidence, i = 35°

angle of refraction, r = ?

Using Snell's law

n' sin i = n sin r

1 x sin 35° = 1.6 x sin  r

 r = 21°

Angle of refraction is equal to 21°.

Now,

distance at which refractive angle comes out

d = 2.5 mm

α be the angle with horizontal surface and incident ray.

α = 90°-21° = 69°

t be the thickness of the film.

So,

tan \alpha = \dfrac{t}{d/2}

tan 61^0 = \dfrac{t}{2.5/2}

t = 2.26 mm

Hence, the thickness of the film is equal to 2.26 mm.

4 0
3 years ago
A rope of length L has circular cross-sectional area A and density rho = m/V , where m is the mass of the rope and V = A · L is
hram777 [196]

Answer: µ = ρ¹ * A¹

Where x=1 and y=1

Explanation: According to the question, the mass per unit length (µ) is related to the density (ρ) and area A are related by the formulae below

µ = ρ * A

The dimension for each of these quantities is given below

Since µ is mass per unit length, unit is Kg/m and the dimension is ML^-1

ρ is density with unit kg/m³ and the dimension is ML^3

A is area with unit m², thus the dimension is M^2

Note that using dimensional analysis means we will be using the 3 fundamental quantities (mass, length and time) in our analysis.

Their dimensions below

Mass = M

Length = L

Time = T

Since the mass per unit length is related to density and area, we have a mathematical equation to provide a solution as shown below

µ = ρ^x * A^y.

By getting the power of x and y we will be able to get the formula that relates the quantities.

This is done by slotting in the dimensions of the respective quantities.

ML^-1 = (ML^-3)^x * (L²) ^y

By using law of indices on the right hand side of the equation, we have that

ML^-1 = (M^x * L^-3x) * (L^2y)

Also applying law of indices on the right hand side, we have that

ML^-1 = (M^x) * (L^-3x +2y)

The next step is to relate equal variables on both sides

For the M variable

M¹ = M^x which results to

x = 1

For the L variable

L^-1 = L^-3x+2y which results to

-1 = - 3x +2y

But x = 1

We have that

-1 = - 3(1) +2y

-1 = - 3 + 2y

-1 +3= 2y

2 = 2y

y = 1

Thus x=1 and y=1 and the formulae that relates the quantities is

µ = ρ¹ * A¹

3 0
3 years ago
A car drives 40 km due east and then 50 km due west .what is the cars overall displacement?
Firdavs [7]

Answer:10 km westExplanation:he go 40 east then 50 west 50-40 is 10 so he displaces 10 km and as west is more than east in terms of km so we will say that it's 10 km west pls mark as brainliest thanks

7 0
3 years ago
Read 2 more answers
Which statements describe the Mercalli scale? Check all that apply.
konstantin123 [22]
<h3><u>Full question:</u></h3>

Which statements describe the Mercalli scale? Check all that apply.

A. This scale measures seismic waves based on their size.

B. This scale rates an earthquake according to how much damage it causes.

C.This scale produces a single rating for earthquakes that reach the surface.

D. This scale uses Roman numerals to rank the damage caused by an earthquake.

E.This scale measures the magnitude of an earthquake based on the size of seismic waves.

<h3><u>Answer:</u></h3>

The Mercalli scale : This scale rates an earthquake according to how much damage it causes and This scale uses Roman numerals to rank the damage caused by an earthquake.

<h3><u>Explanation:</u></h3>

The Modified Mercalli scale is intended to illustrate the consequences of an earthquake, at a contracted station, on tangible characteristics, on modern fittings and human beings.

The Modified Mercalli Intensity value ascribed to a particular site subsequent an earthquake has an extra significant means of severity to the nonscientist than the magnitude because intensity assigns to the outcomes really encountered at that position. This scale is comprised of 12 growing levels of intensity, denoted by Roman numerals, arranging from gradual shaking to catastrophic impairment.

3 0
3 years ago
Name three different avenues by which Thomas Edison received an education
klio [65]
Edison's education is most unique and relevant.

1. The first teacher he had was his mother
2. He found vital lessons and was influenced greatly by the book of R.G. Parker called School of Natural Philosophy
3. Another educating piece he had was a book entitled The Cooper Union for the Advancement of Science and Art

His style of learning was though reading books on a variety of subjects, a self-educating environment that fosters independent learning which can be useful through his life.
5 0
3 years ago
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