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3 years ago

What causes long sightedness?how is it corrected.

Physics

1 answer:

NNADVOKAT [17]3 years ago

4 0

Answer:

Long sight occurs when the eyeball is too short or the lens is too thin, or both. As a result, light rays from near objects are focused behind the retina because the light rays are not converged enough. The image formed on the retina is therefore out of focus.

To correct this problem, people can wear glasses with convex lenses. Light rays from near objects are converged by the convex lenses before entering the eyes, so that light can be focused on the retina to form a sharp image. Additionally, long sight can also be corrected by surgical methods such as LASIK.

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Displacement vectors of 4km north, 2km south, 5km north, 5km south combine to a total displacement of

goldfiish [28.3K]

<u>Answer</u>

The combined displacement is 2km north

<u>Explanation</u>

Since displacement is a vector quantity, we take into account the direction.

Good for us all the displacement vectors are in the same dimension, so we can make north positive and south negative or vice-versa.

We now add to obtain,

$4+-2+5+-5$

This will simplify to

$=4-2+5-5=2$

Therefore the combined displacement is 2km north

5 0

3 years ago

Calculate the change in length of a 90.5 mm aluminum bar that has increased in temperature by from -14.4 oC to 154.6 oC

nignag [31]

Answer:

ΔL = 3.82 10⁻⁴ m

Explanation:

This is a thermal expansion exercise

ΔL = α L₀ ΔT

ΔT = T_f - T₀

where ΔL is the change in length and ΔT is the change in temperature

Let's reduce the length to SI units

L₀ = 90.5 mm (1m / 1000 mm) = 0.0905 m

let's calculate

ΔL = 25.10⁻⁶ 0.0905 (154.6 - (14.4))

ΔL = 3.8236 10⁻⁴ m

using the criterion of three significant figures

ΔL = 3.82 10⁻⁴ m

5 0

3 years ago

A car is traveling at a constant speed on the highway. Its tires have a diameter of 65.0 cm and are rolling without sliding or s

lesya692 [45]

Answer:

Explanation:

The car is rolling without slipping so Vcm= R×ω = 0.325×49 = 16

4 0

3 years ago

If a steady-state heat transfer rate of 3 kW is conducted through a section of insulating material 1.0 m2 in cross section and 2

kaheart [24]

Answer:

$\Delta T = \frac{3000 W *0.025 m}{1 m^2 (0.2 \frac{W}{mK})}= 375 K$

So then the difference of temperature across the material would be $\Delta T = 375 K$

Explanation:

For this case we can use the Fourier Law of heat conduction given by the following equation:

$Q = -kA \frac{\Delta T}{\Delta x}$ (1)

Where k = thermal conductivity = 0.2 W/ mK

A= 1m^2 represent the cross sectional area

Q= 3KW represent the rate of heat transfer

$\Delta T$ is the temperature of difference that we want to find

$\Delta x=2.5 cm =0.025 m$ represent the thickness of the material

If we solve $\Delta T$ in absolute value from the equation (1) we got:

$\Delta T =\frac{Q \Delta x}{Ak}$

First we convert 3KW to W and we got:

$Q= 3 KW* \frac{1000W}{1 Kw}= 3000 W$

And we have everything to replace and we got:

$\Delta T = \frac{3000 W *0.025 m}{1 m^2 (0.2 \frac{W}{mK})}= 375 K$

So then the difference of temperature across the material would be $\Delta T = 375 K$

5 0

3 years ago

Please hurry this is urgent right answers only!!!!!

dem82 [27]

Explanation:

if two individual forces are of equal magnitude and opposite direction, then the force is said to be balanced. when there is an individual force that is not being balanced by a force of equal magnitude and in the opposite direction.

6 0

3 years ago