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3 years ago

Which of the following quantities is a scalar? I need help plz someone help me!!!!!

Physics

2 answers:

Colt1911 [192]3 years ago

5 0

'D' is the scalar. It has size but no direction. The other choices have directions too, so those are vectors.

SSSSS [86.1K]3 years ago

5 0

D is scalar because scalar quantities are on magnitude while vector quantities are magnitude and direction

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For a wire has a circular cross section with a radius of 1.23mm.

Mila [183]

Answer:

$5.731\times 10^{-5}\ m/s$

Decrease

Explanation:

I = Current = 3.7 A

e = Charge of electron = $1.6\times 10^{-19}\ C$

n = Conduction electron density in copper = $8.49\times 10^{28}\ electrons/m^3$

$v_d$ = Drift velocity of electrons

r = Radius = 1.23 mm

Current is given by

$I=neAv_d\\\Rightarrow v_d=\dfrac{I}{neA}\\\Rightarrow v_d=\dfrac{3.7}{8.49\times 10^{28}\times 1.6\times 10^{-19}\times \pi (1.23\times 10^{-3})^2}\\\Rightarrow v_d=5.731\times 10^{-5}\ m/s$

The drift speed of the electrons is $5.731\times 10^{-5}\ m/s$

$v_d=\dfrac{I}{neA}$

From the equation we can see the following

$v_d\propto \dfrac{1}{n}$

So, if the number of conduction electrons per atom is higher than that of copper the drift velocity will decrease.

5 0

3 years ago

A pulsar is a rapidly rotating neutron star. The Crab nebula pulsar in the constellation Taurus has a period of 33.5\times 10^{-

joja [24]

Answer:

$5.25\cdot 10^{40} kg m^2/s$

Explanation:

The angular momentum of the pulsar is given by:

$L=m\omega r^2$

where

$m=2.8\cdot 10^{30} kg$ is the mass of the pulsar

$r = 10.0 km = 1\cdot 10^4 m$ is the radius

$\omega$ is the angular speed

Given the period of the pulsar, $T=33.5\cdot 10^{-3} s$ , the angular speed is given by

$\omega=\frac{2\pi}{T}=\frac{2 \pi}{33.5\cdot 10^{-3}s}=187.5 rad/s$

And so, the angular momentum is

$L=m\omega r^2=(2.8\cdot 10^{30}kg)(187.5 rad/s)(1\cdot 10^4 m)^2=5.25\cdot 10^{40} kg m^2/s$

8 0

3 years ago

John runs 120 meters in 10 seconds and then runs back to where he started in another 10 seconds. Which statement is true? Rememb

atroni [7]

Answer:

Explanation:

A. His speed is 0 m/s

B. His velocity is 12 m/s

C. His velocity is 0 m/s

D. His acceleration is 12 m/s

Total distance traveled by John = 120 + 120 = 240 meters

Total time taken by John to cover the distance = 10 + 10 = 20 s

Average speed of John = total distance traveled/total time taken

= 240/20 = 12 m/s

Hence, the average speed/velocity of John throughout the journey is 12 m/s.

The correct option is B.

4 0

3 years ago

Leah is making a chart to compare and contrast renewable and non-renewable resources. Which of the following would best complete

Sedbober [7]

Answer:

d. Can be replaced at the same rate or faster than they are used

Explanation:

I just took the test, and its the right answer. Your welcome ✌

6 0

3 years ago

Read 2 more answers

Typically during thunderstorms most lightning strikes carry a negative electric charge; only a few carry a positive charge. Thun

Ierofanga [76]

Answer: Option (D) is correct.

Explanation:

Considering the hypothesis elaborated in this comprehension, it's given that areas that tend to lie near forest fires usually have extra positive strikes since smoke carries positively charged particles. In rudimentary term, this states that occurrence of positively charged particles will result in extra positive strikes.

Option (D) states that occurrence of extra positive strikes will be there even weeks after the charge of smoke particles have been dissociated.

Therefore this option, most seriously undermines the hypothesis.

7 0

3 years ago