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2 years ago

Suppose the farthest distance a person can see without visual aid is 53 cm.

Physics

1 answer:

natita [175]2 years ago

8 0

Answer: a. 53cm b. Diverging c. 0.02dioptres

Explanation:

Since the person in question cannot see far object clearly, it shows that the individual is suffering from myopia (short sightedness).

If the object distance (u) is 53cm. for the person to be able to see far way, it means the image must be at infinity. This shows image distance v is infinity. Using the lens formula

1/f = 1/u+1/v

1/f = 1/53 + 1/Infinity

1/f = 1/53 + 0

f=53cm

b) The lens used is concave lens (diverging lens) to diverge all rays outwards

c) Power of a lens P will be 1/53.

P = 0.02dioptres

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A 21 N block rests on a horizontal surface. The coefficients of static and kinetic friction between the surface and the block ar

Georgia [21]

Answer:

a)15 N

b)12.6 N

Explanation:

Given that

Weight of block (wt)= 21 N

μs = 0.80 and μk = 0.60

We know that

Maximum value of static friction given as

Frs = μs m g = μs .wt

by putting the values

Frs= 0.8 x 21 = 16.8 N

Value of kinetic friction

Frk= μk m g = μk .wt

By putting the values

Frk= 0.6 x 21 = 12.6 N

When T = 15 N

Static friction Frs= 16.8 N

Here the value of static friction is more than tension T .It means that block will not move and the value of friction force will be equal to the tension force.

Friction force = 15 N

When T= 35 N

Here value of tension force is more than maximum value of static friction that is why block will move .We know that when body is in motion then kinetic friction will act on the body.so the value of friction force in this case will be 12.6 N

Friction force = 12.6 N

8 0

3 years ago

The sun is 150,000,000 km from the earth.

aniked [119]

Answer:

<h3>What is the angular speed of the earth around the sun? </h3>

It takes the Earth approximately 23 hours, 56 minutes and 4.09 seconds to make one complete revolution (360 degrees). This length of time is known as a sidereal day. The Earth rotates at a moderate angular velocity of

$7.2921159 × 10 {}^{ - 5} \: \: \frac{radians}{second}$

<h3>What is the tangential speed of the earth? </h3>

The earth rotates once every 23 hours, 56 minutes and 4.09053 seconds, called the sidereal period, and its circumference is roughly 40,075 kilometers. Thus, the surface of the earth at the equator moves at a speed of 460 meters per second--or roughly 1,000 miles per hour.

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3 years ago

A comet is in an elliptical orbit around the Sun. Its closest approach to the Sun is a distance of 4.7 1010 m (inside the orbit

Lubov Fominskaja [6]

Answer:

58515.9 m/s

Explanation:

We are given that

$d_1=4.7\times 10^{10} m$

$v_i=9.5\times 10^4 m/s$

$d_2=6\times 10^{12} m$

We have to find the speed (vf).

Work done by surrounding particles=W=0 Therefore, initial energy is equal to final energy.

$K_i+U_i=K_f+U_f$

$\frac{1}{2}mv^2_i-\frac{GmM}{d_1}=\frac{1}{2}mv^2_f-\frac{GmM}{d_2}$

$\frac{1}{2}v^2_i-\frac{GM}{d_1}+\frac{GM}{d_2}=\frac{1}{2}v^2_f$

$v^2_f=2(\frac{1}{2}v^2_i-\frac{GM}{d_1}+\frac{GM}{d_2})$

$v_f=\sqrt{2(\frac{1}{2}v^2_i-\frac{GM}{d_1}+\frac{GM}{d_2})}$

Using the formula

$v_f=\sqrt{v^2_i+2GM(\frac{1}{d_2}-\frac{1}{d_1})}$

$v_f=\sqrt{(9.5\times 10^4)^2+2\times 6.7\times 10^{-11}\times 1.98\times 10^{30}(\frac{1}{6\times 10^{12}}-\frac{1}{4.7\times 10^{10})}$

Where mass of sun= $M=1.98\times 10^{30} kg$

$G=6.7\times 10^{-11}$

$v_f=58515.9 m/s$

4 0

3 years ago

In order to decrease the friction an object experiences, you can either change

Kipish [7]

Answer:

Reduce its weight

Explanation:

For an object on a flat surface, the maximum force of friction experienced by the object is given by:

$F = \mu W$

where

$\mu$ is the coefficient of friction

W is the weight of the object

As we can see from the formula, there are two ways of reducing the friction:

- Decreasing $\mu$ --> this coefficient depends on the material and on the roughness of the surface, so this can be changed by changing the properties of the surface

- Decreasing W, the weight --> this can be done by reducing the mass of the object

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3 years ago

When the balloon sticks to the wall (assuming it sticks to the wall). It is

inn [45]

The answer is false

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2 years ago