IP A charge of 21.0 μC is held fixed at the origin. Part A If a -7.00 μC charge with a mass of 3.50 g is released from rest at the position (0.925 m, 1.17 m), what is its speed when it is halfway to the origin? v = m/s Previous AnswersRequest Answer Incorrect; Try Again; 11 attempts remaining Part BPart complete Suppose the -7.00 μC charge is released from rest at the point x = 12(0.925m) and y = 12(1.17m). When it is halfway to the origin, is its speed greater than, less than, or equal to the speed found in part A? Greater than the speed found in part A Lee than the speed found part in A Equal to the speed found in part A Previous Answers Correct Part C Find the speed of the charge for the situation described in part B. v = m/s

1. A 3-phase, 5 kVA, 208 V, 4-pole, 60 Hz, star-connected synchronous generator has negligible stator winding resistance and a synchronous reactance of 8 Ω per phase at the rated terminal voltage. The generator is connected in parallel to a 3-phase, 208 V, 60 Hz infinite bus. All losses may be neglected.

a)   Determine the excitation voltage and the power angle when the machine is delivering rated apparent power at 0.8 PF lagging.

b)   If the field excitation is increased by 20 % without changing the prime mover power, find the stator current, power factor, and reactive power supplied by the machine.

c)   With the field current as in (a), determine the maximum power with which the generator can be supplied without losing synchronism? What are the corresponding stator current and power factor at this maximum power condition?

PLEASE ANSWER ALL 3 WILL THUMBS UP

1) A force of 540 newtons stretches a spring 3 meters. A mass of 45 kilograms is attached to the end of the spring and is initially released from the equilibrium position with an upward velocity of 8 m/s. Find the equation of motion.

x(t)=? m

2) Find the charge on the capacitor and the current in an LC-series circuit when L = 0.1 h, C = 0.1 f, E(t) = 100 sin(γt) V, q(0) = 0 C, and i(0) = 0 A

q(t)= ?

i(t)= ?

3) Find the steady state current i_p(t) in an LRC-series circuit when L = 1/2 h, R= 20 ohms, C= 0.001 f and E(t) = 400sin(60t)+500cos(40t) V

i_p(t)= ?

A 230 V, 500 rpm, 100 A separately- excited dc motor has an armature resistance of 0.1 ohms. The motor is driving, under rated conditions, a load whose torque is constant and independent of speed. The speeds below the rated speed are obtained with armature voltage control (with full field) and the speeds above the rated speed are obtained by field control (with rated armature voltage).

1. What motor terminal voltage is needed to run it at 400 rpm?

2. By what amount should flux be reduced to get a motor speed of 800 rpm?

Neglect the motor’s rotational losses.

3.The separately- excited motor of the previous problem is now coupled to an overhauling load with a torque of 800 N-m. Determine the speed at which the motor can hold the loadby regenerative braking. Source voltage is 230 V. Neglect the motor’s rotational losses.

Three different states participate in a poll of attitudes toward two possible energy policies(Policy I, and Policy II . The results are given in the table below:

State

policy choice Gas Coal Other

I 50 59 161 II 80 71 129

To test the null of association (Independence) between the type of the state and the policy choice. Use ALPHA=.01, then (

A) Test Stat: LaTeX: \chi χ 2 LaTeX: \approx ≈ 10.384 ; p-vLaTeX: \approx ≈ .009 ; Dec: Reject the null

(B) Test Stat: LaTeX: \chi χ 2 LaTeX: \approx ≈ 11.384 ; p-v LaTeX: \approx ≈ .003 ; Dec: Reject the null

(C) Test Stat : LaTeX: \chi χ 2 LaTeX: \approx ≈ 11.384 ; p-v LaTeX: \approx ≈ .030 ; Dec: Reject the null

Suppose on 31-Dec-2019 you entered into a forward contract to buy one share of stock XYZ for delivery price = L = $50 with delivery date 31-Dec-2020.  You enter t and S(t) into your formula for V(S,t) to figure out today’s value of the contract.  Now suppose you learn to your surprise that interest rates are not constant; they can change in an uncertain way over the time period from today to 31-Dec-2020.

[A]  Assume that today’s stock price and the interest rates that prevail today have not changed.   Will the forward price that you compute today (for delivery date 31-Dec-2020) change because of your revised view that future interest rates are uncertain?

[B]  Will V(S,t), the value of the forward contract, change?  Why or why not?

An certain brand of upright freezer is available in three different rated capacities: 16 ft³, 18 ft³, and 20 ft³. Let X = the rated capacity of a freezer of this brand sold at a certain store. Suppose that X has the following pmf.

(a) Compute E(X), E(X²), and V(X).

(b) If the price of a freezer having capacity X is 60X − 650, what is the expected price paid by the next customer to buy a freezer?

(c) What is the variance of the price paid by the next customer?

(d) Suppose that although the rated capacity of a freezer is X, the actual capacity is h(X) = X − 0.009X². What is the expected actual capacity of the freezer purchased by the next customer?

Two isolated concentric conducting spherical shells have radii R1=0.5 m and R2=1 m,

uniform charges q1=+2.0 μC and q2=+1 μC, and negligible thickness. Assume that V=0 at infinity.​

(a) What is the magnitude of the electric field at a radial distance of r=4 m?
(b) What is the magnitude of the electric field at a radial distance of r=0.7 m?
(c) What is the magnitude of the electric field at a radial distance of r=0.2 m?
(d) What is the potential at r=4 m?
(e) What is the potential at r=1 m?
(f) What is the potential at r=0.7 m?
(g) What is the potential at r=0.5 m?
(h) What is the potential at r=0.2 m?
(i) What is the potential at r=0 m?
(j) sketch E(r) and V(r).​

Both a call and a put currently are traded on stock XYZ; both have strike prices of $35 and expirations of 6 months.

a. What will be the profit to an investor who buys the call for $5 in the following scenarios for stock prices in 6 months? (i) $40; (ii) $45; (iii) $50; (iv) $55; (v) $60. (Leave no cells blank - be certain to enter "0" wherever required. Negative amounts should be indicated by a minus sign. Round your answers to 1 decimal place.)

b. What will be the profit to an investor who buys the put for $7.5 in the following scenarios for stock prices in 6 months? (i) $40; (ii) $45; (iii) $50; (iv) $55; (v) $60. (Leave no cells blank - be certain to enter "0" wherever required. Negative amounts should be indicated by a minus sign. Round your answers to 1 decimal place.)

A rail gun uses electromagnetic forces to accelerate a projectile to very high velocities. The basic mechanism of acceleration is relatively simple and can be illustrated in the following example. A metal rod of mass 40.0 g and electrical resistance 0.200 Ωrests on parallel horizontal rails that have negligible electric resistance. The rails are a distance L = 10.0 cm apart. (Figure 1) The rails are also connected to a voltage source providing a voltage of V = 5.00 V .
The rod is placed in a vertical magnetic field. The rod begins to slide when the field reaches the value B = 7.84×10⁻² T . Assume that the rod has a slightly flattened bottom so that it slides instead of rolling. Use 9.80 m/s2 for the magnitude of the acceleration due to gravity.

Find μs, the coefficient of static friction between the rod and the rails.