A transformer is to be used to provide power for a computer disk drive that needs 6.4 V (rms) instead of the 120 V (rms) from the wall outlet. The number of turns in the primary is 300, and it delivers 500 mA (the secondary current) at an output voltage of 6.4 V (rms). (a) Should the transformer have more turns in the secondary compared to the primary, or fewer turns

Answer:

The secondary coil should have fewer turns compared to the primary coil.

Explanation:

[tex]N_p[/tex] = Number of turns in primary coil = 300

[tex]N_s[/tex] = Number of turns in secondary

[tex]V_p[/tex] = Voltage in primary coil = 120 V

[tex]V_s[/tex] = Voltage in secondary coil = 6.4 V

We have the relation

[tex]\dfrac{N_p}{N_s}=\dfrac{V_p}{V_s}\\\Rightarrow N_s=\dfrac{N_p}{V_p}\times V_s\\\Rightarrow N_s=\dfrac{300}{120}\times 6.4\\\Rightarrow N_s=16[/tex]

The secondary coil has 16 turns which is less than the turns in the primary coil.

A jet aircraft is in level flight at an altitude of 30,000 ft with an airspeed of 500 ft/s. The aircraft has a gross weight of 19,815 lb, a wingspan of 53.3 ft, and an average chord length of 6 ft. The Oswald efficiency factor is 0.81 and the zero-lift drag coefficient is equal to 0.02. The jet has two turbofan engines, each producing a maximum thrust of 3,650 lb at sea level.

Required:
a. Create a plot of the drag polar for this aircraft for CL from 0 to 5. Plot CL on the vertical axis, CD on the horizontal axis, and do not include negative CL values.
b. What is the total drag coefficient at the flight condition described above?
c. What is the required thrust for level flight at this altitude in lb?
d. If the pilot runs the engines at maximum thrust, what is the instantaneous rate of climb at this altitude and velocity?

8. Which of these plastics is a themoplastic - melts or softens with heat.
Acrylic
Bakelite
Polyester resin
Melamine
Epoxy Resin

Could someone please help me, this is very urgent, I will pay an extra bonus if done correct.

7.13 An intersection approach has a saturation flow rate of 1500 veh/h, and vehicles arrive at the approach at the rate of 800 veh/h. The approach is controlled by a pretimed signal with a cycle length of 60 seconds and D/D/1 queuing holds. Local standards dictate that signals should be set such that all approach queues dissipate 10 seconds before the end of the effective green portion of the cycle. Assuming that approach capacity exceeds arrivals, determine the maximum length

Hot engine oil with heat capacity rate of 4440 w/k (product of mass flow rate and specific heat) and an inlet temperature of 150°c flows through a double pipe heat exchanger. the double pipe heat exchanger is constructed of a 1.5-m-long copper pipe (k = 250 w/m·k) with an inner tube of inside diameter 2 cm and outside tube diameter of 2.25 cm. the inner diameter of the outer tube of the double pipe heat exchanger is 6 cm. oil flowing at a rate of 2 kg/s through inner tube exits the heat exchanger at a temperature of 50°c. the cold fluid, i. e., water enters the heat exchanger at 20°c and exits at 70°c. assuming the fouling factor on the oil side and water side to be 0.00015 m2 ·k/w and 0.0001 m2 ·k/w, respectively, determine the overall heat transfer coefficient on inner and outer surface of the copper tube.