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Tasya [4]
2 years ago
13

A wire of length L and cross-sectional area A has resistance R.

Physics
1 answer:
Leona [35]2 years ago
6 0

Answer:

The resistance R stretched of the wire if it is stretched to twice its original length is [Δ(2L) / A ]* 2

Explanation:

Original Resistance R = ΔL / A

Given length is doubled

New length  L' = 2L

New Volume is constant, resistivity and density of material is also assumed to be constant

AL = A'L'

AL = A'(2L)

A' = AL / 2L

A' = A / 2

∴ new Resistance R' = ΔL' / A'

                                 =  Δ(2L) / A/2

                                  = [Δ(2L) / A ]* 2

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The Earth's axis of rotation is tilted. Because of this, the amount of sunlight an area on the planet receives each day varies
Sergio039 [100]

Answer: The Northern Hemisphere experiences the start of <u>summer</u>

Explanation:

Due to this tilt in Earth's axis of rotation, some regions receive different amounts of sunlight according to the seasons of the year. These variations are more evident near the poles and softer or imperceptible near the equator. This explains the fact that while in the northern hemisphere it is summer and there are high temperatures (because the Sunlight incides more perpendicularly in this area during this season), in the southern hemisphere it is winter and very low temperatures are recorded, and vice versa.  

In this sense, according to the image the Earth is at the point of its orbit in which, due to the inclination of its axis, the North Pole is closer to the Sun.  

In other words, the northern hemisphere is tilted toward the Sun, and this astronomical phenomenon brings the summer season for the Northern Hemisphere.

4 0
3 years ago
Read 2 more answers
A 5 kg ball rolling at 1.0 m/s hits a 15 kg ball at rest. The balls stick together after the collision What is the
Reika [66]

Answer:

0.25m/s

Explanation:

Given parameters

m₁  = 5kg

v₁ = 1.0m/s

m₂ = 15kg

v₂ = 0m/s

Unknown:

velocity after collision = ?

Solution:

Momentum before collision and after collision will be the same. For inelastic collision;

    m₁v₁ + m₂v₂  = v(m₁ + m₂)

Insert parameters and solve for v;

   5 x 1  + 15 x 0 = v (5 + 15 )

          5  = 20v

          v = \frac{5}{20}   = 0.25m/s

5 0
3 years ago
half life worksheet answer key 3. What percent of a sample As-81 remains un-decayed after 43.2 seconds
Ivahew [28]

The final mass after decay can be obtained by using under given relation:

half life period of As-81 = 33 seconds

mf = mi x (1/2^n)

= 100 x ( 1/2^(43.2/33))

= 40.4 %


3 0
3 years ago
The potential energy of a watermelon is 15.0 J. The watermelon is 3.0 m high. What is the mass of the watermelon?
maks197457 [2]

Answer:

m = 0.51[kg]

Explanation:

Potential energy is defined as the product of mass by gravity by height.

E_{pot}=m*g*h

where:

Epot = potential energy = 15 [J]

m = mass [kg]

g = gravity acceleration = 9.8 [m/s²]

h = elevation = 3 [m]

Now replacing:

E_{pot}=m*g*h\\15=m*9.8*3\\m = 0.51[kg]

5 0
3 years ago
Does the air exert a buoyant force on all objects in air or only on objects such as balloons that are very light for their size?
Citrus2011 [14]

Answer:

See explanation

Explanation:

Solution:-

Buoyancy is the force that causes objects to float. It is the force exerted on an object that is partly or wholly immersed in a fluid. Buoyancy is caused by the differences in pressure acting on opposite sides of an object immersed in a static fluid. It is also known as the buoyant force. Buoyancy is the phenomena due to Buoyant Force.

It is as an upward force exerted by a fluid that opposes the weight of an object immersed in a fluid. As we know, the pressure in a fluid column increases with depth. Thus, the pressure at the bottom of an object submerged in the fluid is greater than that at the top. The difference in this pressure results in a net upward force on the object which we define as buoyancy.

- The formula for buoyant force (Fb) is given:

                           Fb = ρ*g*V

- The force acts on all objects. However, it depends on the fluid density and amount of volume displaced.

- The Buoyant force exerted by air with density = 1.225 kg/m^3 on an object with volume (V) is:

                          Fb = ρ*g*V = 1.225*9.81*V = 12.02*V

- For the similar object with mass (m), the downward weight would be:

                           W = m*g

- For the object to float the buoyant force (Fb) must be greater than weight of the object:

                          Fb > W

                          12.02*V > m*9.81

                          V / m > 0.816

- The ratio of V / m must be at-least = 0.816.

- Assuming the object is fully immersed in air, then the volume displaced V = ρ_material*V

                         ρ_material < 1 / 0.816

                        ρ_material < 1.225 or ( ρ_air )

- So the for an object to float in air its material density must always be less than that of air. That why in balloons lighter gas is used which have density less than that of air like Helium.          

4 0
3 years ago
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