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3 years ago

1 give reason

Physics

1 answer:

Anastaziya [24]3 years ago

4 0

Answer:

A. The melting of ice is both a desirable and undesirable change because, ice is needed to melt so as to make liquid water available for animal and plant use and consumption and also to release the energy used in the fusion process of ice formation. Melting of ice is undesirable because melting ice liberate water slowly, and the water liberated can erode surface soil. Melting ice reduces the available heat sink on earth and also reduces the available stored up fresh water supply on earth.

B. The appearance of hailey comet once every 72 year is a periodic change because it's motion around the solar system is repeated with time. The reason for this highly elliptical and eccentric path of motion is largely due to the gravitational effect of the sun and the planets on the comet.

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If a leaf falls from a tree, has work been done on the leaf? Explain.

mihalych1998 [28]

Answer:

Hope this helps!

5 0

2 years ago

A spherical, conducting shell of inner radius r1= 10 cm and outer radius r2 = 15 cm carries a total charge Q = 15 μC . What is t

lutik1710 [3]

a) E = 0

b) $3.38\cdot 10^6 N/C$

Explanation:

We can solve this problem using Gauss theorem: the electric flux through a Gaussian surface of radius r must be equal to the charge contained by the sphere divided by the vacuum permittivity:

$\int EdS=\frac{q}{\epsilon_0}$

where

E is the electric field

q is the charge contained by the Gaussian surface

$\epsilon_0$ is the vacuum permittivity

Here we want to find the electric field at a distance of

r = 12 cm = 0.12 m

Here we are between the inner radius and the outer radius of the shell:

$r_1 = 10 cm\\r_2 = 15 cm$

However, we notice that the shell is conducting: this means that the charge inside the conductor will distribute over its outer surface.

This means that a Gaussian surface of radius r = 12 cm, which is smaller than the outer radius of the shell, will contain zero net charge:

q = 0

Therefore, the magnitude of the electric field is also zero:

E = 0

Here we want to find the magnitude of the electric field at a distance of

r = 20 cm = 0.20 m

from the centre of the shell.

Outside the outer surface of the shell, the electric field is equivalent to that produced by a single-point charge of same magnitude Q concentrated at the centre of the shell.

Therefore, it is given by:

$E=\frac{Q}{4\pi \epsilon_0 r^2}$

where in this problem:

$Q=15 \mu C = 15\cdot 10^{-6} C$ is the charge on the shell

$r=20 cm = 0.20 m$ is the distance from the centre of the shell

Substituting, we find:

$E=\frac{15\cdot 10^{-6}}{4\pi (8.85\cdot 10^{-12})(0.20)^2}=3.38\cdot 10^6 N/C$

4 0

3 years ago

The surface is tilted to an angle of 37 degrees from the horizontal, as shown above in Figure 3. The blocks are each given a pus

hoa [83]

Answer:

Incomplete question: "Each block has a mass of 0.2 kg"

The speed of the two-block system's center of mass just before the blocks collide is 2.9489 m/s

Explanation:

Given data:

θ = angle of the surface = 37°

m = mass of each block = 0.2 kg

v = speed = 0.35 m/s

t = time to collision = 0.5 s

Question: What is the speed of the two-block system's center of mass just before the blocks collide, vf = ?

Change in momentum:

$delta(P)=F*delta(t)$

$P_{f} -P_{i}=F*delta(t)$

$2m(v_{f} -v_{i})=F*delta(t)$

$v_{i} =0.35-0.35=0$

It is neccesary calculate the force:

$F=(m+m)*g*sin\theta$

Here, g = gravity = 9.8 m/s²

$F=(0.2+0.2)*9.8*sin37=2.3591N$

$v_{f} =\frac{F*delta(t)}{2m} =\frac{2.3591*0.5}{2*0.2} =2.9489m/s$

6 0

2 years ago

20. A semiconductor is a

Stells [14]

Answer:

D. crystalline solid that conducts current under certain conditions

Explanation:

Semiconductors are crystalline solids that has the ability to conduct electrical currents but on certain conditions e.g heat. The conduction of semiconductors is less than that of conductors (metals) but more than insulators (nonmetals), hence, they are said to be intermediates of conductors and insulators in terms of electrical conductivity.

Examples of semiconductors are silicon, boron, carbon, germanium, arsenic etc.

5 0

2 years ago

Describe a situation where you add heat to a substance or material but there is no change in temperature. What does this look li

Alisiya [41]

ONE CAN perform this by doing an ideal experiment
by creating an isothermal system
its like you supply heat to a body and that body is present at very low temperature the amount of heat you supply is equal to the amount of heat lost by that body due to difference in the temperature of the body and the surrounding. heating curve will be constant as there is no change in the internal energy of the system ..

6 0

3 years ago