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A small first-aid kit is dropped by a rock climber who is descending steadily at -1.25 m/s. After 2.5 seconds, what is the veloc

postnew [5]

The genuine answer here

7 0

2 years ago

A hole is drilled in a metal plate. When the metal is raised to a higher temperature, what happens to the diameter of the hole?

zysi [14]

Answer:

The diameter of the hole increases

Explanation:

Metals expand and contract with temperature. Whenever metal is heated, it usually expands in relation to its thermal expansivity. This expansion leads to a slight increase in surface area.

Once the surface area of the metal changes, this means that the dimensions of the whole metal surface changed. As a result, the diameter of the hole drilled in the metal plate will change also. In our case, the diameter of the hole will increase.

4 0

3 years ago

Two satellites, A and B are in different circular orbits

jek_recluse [69]

Answer:

The ratio of the orbital time periods of A and B is $\frac{1}{2}$

Solution:

As per the question:

The orbit of the two satellites is circular

Also,

Orbital speed of A is 2 times the orbital speed of B

$v_{oA} = 2v_{oB}$ (1)

Now, we know that the orbital speed of a satellite for circular orbits is given by:

$v_{o} = \farc{2\piR}{T}$

where

R = Radius of the orbit

Now,

For satellite A:

$v_{oA} = \farc{2\piR}{T_{a}}$

Using eqn (1):

$2v_{oB} = \farc{2\piR}{T_{a}}$ (2)

For satellite B:

$v_{oB} = \farc{2\piR}{T_{b}}$ (3)

Now, comparing eqn (2) and eqn (3):

$\frac{T_{a}}{T_{b}} = \farc{1}{2}$

6 0

2 years ago

Ethanethiol (; also called ethyl mercaptan) is commonly added to natural gas to provide the ""rotten egg"" smell of a gas leak.

Tju [1.3M]

Answer:

S = 27500J / 308.15molK

Explanation:

Entropy measures the degree of disorganization of a system. It is measured in the entropy change that is equal to the heat exchanged divided by the temperature at which the process occurs.

S2-S1 = Q / T

S = entropy

Q = heat = 27.5 kJ / mol * 1000J / 1KJ = 27500J / mol

T = temperature = 35 + 273.15 = 308.15K

units = J / molK

S = 27500J / 308.15molK

3 0

3 years ago

Andrea's near point is 20.0 cm and her far point is 2.0 m. Her contact lenses are designed so that she can see objects that are

Shalnov [3]

Answer:

the closest distance that she can see an object clearly when she wears her contacts is 22.2 cm

Explanation:

Given the data in the question,

near point = 20 cm

far point = 2 m = 200 cm

Now, for an object that is infinitely far away, the image is at is its far point.

so using the following expression, we can determine the focal length

1/f = 1/i + 1/o

where f is the focal length, i is the image distance and o is the object distance.

here, far point i = 2 m = 200 cm and v is ∞

so we substitute

1/f = 1/(-200 cm) + 1/∞

f = -200 cm

Also, for object at its closest point, the image appear at near point,

so

1/f = 1/i + 1/o

we make o the subject of formula

o = ( i × f ) / ( i - f )

given that near point i = 20 cm

we substitute

o = ( -20 × -200 ) / ( -20 - (-200) )

o = 4000 / 180

o = 22.2 cm

Therefore, the closest distance that she can see an object clearly when she wears her contacts is 22.2 cm

4 0

3 years ago