If an object travels 245 km in 5 hours, what was the speed of the object?

What current flows through a 2.54cm diameter rod of pure silicon that is 20cm long when 1000V is applied?

vfiekz [6]

Answer: $0.0039\ A$

Explanation:

Given

Diameter of the rod $d=2.54\ cm$

length of rod is $l=20\ cm$

Resistivity of silicon is $\rho=6.4\times 10^2\ \Omega-m$

cross-section of the rod $A$

$\Rightarrow A=\dfrac{\pi d^2}{4}\\\\\Rightarrow A=\dfrac{3.142\times 2.54^2\times 10^{-4}}{4}\\\\\Rightarrow A=5.067\times 10^{-4}\ m^2$

Resistance of rod is R

$\Rightarrow R=\dfrac{\rho l}{A}$

$\Rightarrow R=\dfrac{640\times 0.20}{5.067\times 10^{-4}}\\\\\Rightarrow R=25.26\times 10^4\ \Omega$

Current is given by

$\Rightarrow I=\dfrac{V}{R}\\\\\Rightarrow I=\dfrac{1000}{25.26\times 10^4}\\\\\Rightarrow I=0.0039\ A$

3 0

2 years ago

A rock is thrown horizontally from a high building at 33.8 m/s. What is the magnitude of its velocity 4.25 s later?

Alex17521 [72]

<h2>Answer:53.63 $ms^{-2}$ </h2>

Explanation:

The equations of motion used in this question is $v=u+at$

When a object is projected horizontally from a sufficiently height,the x-component of acceleration remains zero because there is no force that drags the object in x direction.

But,due to gravity,the object accelerates downward at a rate of $9.8ms^{-2}$ .

In X-Direction,

Given that initial velocity= $u_{x}$ = $33.8ms^{-1}$

Using $v=u+at$ ,

$v_{x}=33.8+(0)4.25=33.8ms^{-1}$

In Y-Direction,

Given that initial velocity= $u_{x}$ = $0ms^{-1}$

Using $v=u+at$ ,

$v_{y}=0+(9.8)4.25=41.65ms^{-1}$

$v=\sqrt{v_{x}^{2}+v_{y}^{2}}$

$v=\sqrt{1142.44+1734.72}=\sqrt{2877.163}=53.63ms^{-1}$

7 0

3 years ago

Astronomers discover a bright X-ray source in the Milky Way. They see no counterpart in the optical bands, but it has another st

VladimirAG [237]

Answer:

a. a black hole

Explanation:

X-ray emission from the central degrees of the Milky Way Bright X-ray emission traces the coherent edge brightened shell-like feature, dubbed the northern chimney, located north of Sgr A* and characterized by a diameter of about 160 pc. On the opposite side, the southern chimney appears as a bright linear feature. Bright X-ray emission is observed at high latitude

8 0

3 years ago

Pls help im begging you

Lostsunrise [7]

Answer:

I think it's TRUE because forces change an object's motion but dont quote me on it ok? Cause I'm not a 100 percent sure

7 0

3 years ago

Match the theory to the statement that best describes it. 1. big bang. 2. steady state. 3.osscillating universe. 4. inflation Ch

Gre4nikov [31]

Explanation :

(1) Big bang : (1) The most accepted theory on the origin of the universe.

This theory shows the expanding of the universe from high density and high-temperature states.

(2) Steady state : (3) All is the same and will always stay the same.

Steady state means that the properties of any system remain the same always.

(3) Oscillating universe : (4) Agrees with the big bang theory but insists the universe expanded much quicker.

Oscillating universe theory is the result of big bang theory.

(4) Inflation Choices : (2) it's like an inflating and deflating balloon that never stops.

In cosmology, cosmic inflation or deflation is just the expanding and contraction of the universe.

So, the statements and the choices are related as:

(1)-(1)

(2)- (3)

(3)-(4)

(4)-(2)

8 0

3 years ago

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