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rewona [7]
3 years ago
9

Two point charges of -7uC and 4uC are a distance of 20

Physics
2 answers:
aivan3 [116]3 years ago
8 0

Answer:

Approximately 0.979 J.

Explanation:

Assume that the two charges are in vacuum. Apply the coulomb's law to find their initial and final electrical potential energy \mathrm{EPE}.

\displaystyle \mathrm{EPE} = \frac{k \cdot q_1 \cdot q_2}{r},

where

  • The coulomb's constant k = 8.99\times 10^{9}\; \rm N\cdot m^{2} \cdot C^{-2},
  • q_1 and q_2 are the sizes of the two charges, and
  • r is the separation of (the center of) the two charges.

Note that there's no negative sign before the fraction.

Make sure that all values are in SI units:

  • q_1 = -7\rm \;\mu C = -7\times 10^{-6}\; C;
  • q_2 = 4\rm \;\mu C = 4\times 10^{-6}\; C;
  • Initial separation: \rm 20\; cm = 0.20\; cm;
  • Final separation: \rm 90\; cm = 0.90\; cm.

Apply Coulomb's law:

Initial potential energy:

\begin{aligned} \frac{k \cdot q_1 \cdot q_2}{r} &= \frac{8.99\times 10^{9}\times (-7\times 10^{-6})\times 4\times 10^{-6}}{0.20}\\&= \rm -1.2586\; J\end{aligned}.

Final potential energy:

\begin{aligned} \frac{k \cdot q_1 \cdot q_2}{r} &= \frac{8.99\times 10^{9}\times (-7\times 10^{-6})\times 4\times 10^{-6}}{0.90}\\&= \rm -0.279689\; J\end{aligned}.

The final potential energy is less negative than the initial one. In other words, the two particles gain energy in this process. The energy difference (final minus initial) will be equal to the work required to move them at a constant speed.

\begin{aligned}\text{Work required} &= \text{Final EPE} - \text{Initial EPE}\\&= \rm  -0.279689\; J - (-1.2586\; J)\\&\approx 0.979\; J\end{aligned}.

olga2289 [7]3 years ago
3 0

Answer:

Answer is c

Explanation:

trust me.

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On a good night, the front row of the Twisted Sister concert would surely result in a 120 dB sound level. An IPod produces 100 d
cricket20 [7]

Answer:

100 iPods

Explanation:

The deciBell scale is logarithmic, and thus, it turns multiplying into adding.

Initially, it was the Bell scale, purely logarithmic, where "times 10" is translated into "plus 1" (just like normal logs). However, the steps became too big and so they divided the Bell in 10 parts, the deciBell.

The levels above could well have been called 10B and 12B.

Usually, we define the dB scale for intensity as:

I(dB) = 10•log(I)

Thus,

I = 10^(I(dB)/10)

Now 120 dB gives us units of I = 10^(120/10) = 10^12 Pa (assume the dB are measured to 1 Pa) and 100 dB is 10^10 Pa.

Thus, we would need 100 ipods to get the same intensity

8 0
3 years ago
A racetrack has the shape of an inverted cone, as the drawing shows. On this surface the cars race in circles that are parallel
sergey [27]

Answer:

The value of d is 183.51 m.

Explanation:

Given that,

Speed of car = 34.0 m/s

Suppose The car race in the circle parallel to the ground surface is at an angle 40°

The radius of circular path r = d\cos\theta

Normal force acting on the car = N

We need to calculate the value of d

Using component of normal force

The horizontal component of normal force is equal to the gravitational force.

N\cos\theta=mg....(I)

The vertical component of normal force is equal to the centripetal force

N\sin\theta=\dfrac{mv^2}{r}.....(II)

Divided equation (I) by equation (II)

\tan\theta=\dfrac{v^2}{gr}

Put the value of g

\tan\theta=\dfrac{v^2}{g\times d\cos\theta}

v^2=\tan\theta\times g\times d\cos\theta

v^2=g\times d\sin\theta

d=\dfrac{v^2}{g\sin\theta}

Put the value into the formula

d=\dfrac{(34.0)^2}{9.8\times\sin40}

d=183.51\ m

Hence, The value of d is 183.51 m.

3 0
3 years ago
John is riding the bus to the next samuell football game. The bus is traveling to the right at 20 m/s and Jon is walking towards
Elenna [48]

Answer:

Vrel_jon's = 15 [m/s] to the right

Explanation:

Relative velocity is defined as the relative motion between two bodies, taking into account the directions of motion.

Relative velocity is defined as the relative motion between two bodies, taking into account the directions of motion. The relative velocity is defined as the algebraic sum of the velocities, if the movements are opposite the vectors are subtracted, as will be done below.

Vrel = 20 - 5 = 15 [m/s]

A person watching Jon sees him moving to the right at a speed of 15 [m/s]

4 0
3 years ago
A bat hits a moving baseball. If the bat delivers a net eastward impulse of 1.3 N-s and the ball starts with an initial horizont
Georgia [21]

Answer:

141.30grams

Explanation:

First, denote our known values;

J=1.3N-s(+,east)\\u=-3.8ms^-^1(-,west)\\v=5.4ms^-^1(+,east)\\m=?

Mass is impulse divided by change in velocity:

m=\frac{J}{v-u}\\=\frac{1.3}{5.4--3.8}\\\\=\frac{1.3}{9.2}\\=0.1413Kgs

Hence, the mass of the ball is 141.30grams

3 0
3 years ago
A research vessel is mapping the bottom of the ocean using sonar. It emits a short sound pulse called "ping" downward. The frequ
Svetradugi [14.3K]

Answer:

d = 4180.3m

wavelengt of sound is 0.251m

Explanation:

Given that

frequency of the sound is 5920 Hz

v=1485m/s

t=5.63s

let d represent distance from the vessel to the ocean bottom.

an echo travels a distance equivalent to 2d, that is to and fro after it reflects from the obstacle.

velocity=\frac{distance}{time}\\\\ v=\frac{2d}{t} \\\\vt=2d\\\\d=\frac{vt}{2}

d=\frac{1485*5.63}{2}\\d= 4180.3m

wavelengt of sound is \lambda = v/f

= (1485)/(5920)

= 0.251 m

7 0
3 years ago
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