Resistivity Q&A: Expert Assistance

Prove $2^{135} + 3^{133} < 4^{108}$

Waylon Mcbride 2022-04-12

The particle is falling down, and x is measured in down direction.
$x^{″} = g - k v^{4} ⟹ v \frac{d v}{d x} = g - k v^{4}$
Solving this I get
$\frac{1}{4 \sqrt{g k}} \log (\frac{\sqrt{k} v^{2} - \sqrt{g}}{\sqrt{k} v^{2} + \sqrt{g}}) = x + c$
It is falling from rest, i.e x=0,v=0, using this initial condition I get $\log (- 1)$ on the LHS. Is something wrong with the solution. I check that integral is correct.

Jaime Coleman 2022-04-12

Prove or Disprove that $| \frac{e^{2 i θ} - 2 e^{i θ} - 1}{e^{2 i θ} + 2 e^{i θ} - 1} | = 1$
This is a step in an attempt to solve a much larger problem, thus I'm fairly sure it's true but not absolutely sure. It looks like it should be simple but it's resisted all my attempts so far.

Alisa Durham 2022-04-06

A submarine of mass m is travelling at max power and has engines that deliver a force F at max power to the submarine. The water exerts a resistance force proportional to the square of the submarine's speed v.
The submarine increases its speed from $v_{1}$ to $v_{2}$ , show that the distance travelled in this period is $\frac{m}{2 k} \ln \frac{F - k v_{1}^{2}}{F - k v_{2}^{2}}$ where k is a constant.
I've found $\frac{d v}{d t} = \frac{1}{m} (F - k v^{2})$ using $\sum F = m a$ but I am struggling to progress further using integration or the fact that $\frac{d v}{d t} = v \frac{d v}{d x} = \frac{d}{d x} (\frac{1}{2} v^{2}) = \frac{d^{2} x}{d t^{2}}$ which is how I've been taught to solve resisted motion questions.

Maiclubk 2021-04-25

Flux through a Cube (Eigure 1) A cube has one corner at the origin and the opposite corner at the point (L, L, L). The sides of the cube are parallel to the coordinate planes

necessaryh 2021-03-01

Answer the following T/F questions based on the behavior of the circuit in the above Figure 5:
(1) A transient current flows for a short time after the RELAY is switched to either the N.O.("normally open") or N.C. ("normally closed") position.
(2)The transient currents that flow in this experiment decays exponentially to zero.
(3)The capacitor charge Q exponentially decays to zero when the RELAY is thrown to position N.O.
(4)When the current I is positive, the capacitor charge Q is decreasing.
(5)When the current I is positive, the measured VOLTAGE IN 2 will be negative.
(6)When the capacitor charge Q is positive, the measured VOLTAGE IN 1 is positive.
(7)The quantity t1/2=? ln 2 is called the half-life of an exponential decay, where ?=RC is the time constant in an RC circuit. The current in a discharging RC circuit drops by half whenever t increases by $t_{\frac{1}{2}}$ . For a circuit with R=2 k? and C=3 ?F, if the current is 6 am at t=5 ms, at what time (in ms) will the current be 3 mA?

Dolly Robinson 2021-01-31

A 12-V battery is connected to terminals A and B in the above Figure.
(a) Given that R = 75 ohms, find the current in each resistor.
(b) Suppose the value of R is increased. For each resistor in turn, state whether the current flowing through it increases or decreases. Explain.

Phoebe 2020-11-26

Consider the three circuits shown above. All the resistors and all the batteries are identical. Which of the statements are true and which ones are false?
1)The power dissipated in circuit A is twice the power dissipated in circuit B.
2) The current through a resistor is the same in circuits A and C.
3) The current through a resistor is the same in circuits A and B.
4) The voltage across a single resistor in circuit C is twice the voltage across a single resistor in circuit B.
5) The total power dissipated in circuit C is twice the total power dissipated in circuit B.

Electric Engineering and robotics will require the studies of the electric current and resistivity. These are meant for the selection of the materials that are used in electrical and electronic components. Therefore, the resistivity problems with solutions will revolve around conductors and the resistant wires as you calculate the resistivity. The answers will include formulas that must be used first, so you can see and understand how things work. The resistivity examples can also be related to statistical data, which means that you can use the solutions as the templates with the different numbers where you simply replace the data.

Electric current

Unlock Resistivity with Step-by-Step Examples and Expert Guidance