Engineering College

It is common to specify battery capacity, the amount of stored energy, with units of ampere-hours (Ah). A particular 12 V lead acid battery has a capacity of 80 Ah. That is, the battery stores enough energy to supply 1 A for 80 hours, or 80 A for 1 hour, or 20 A for 4 hours, and so on. Note that amperes times hours give units of charge, not energy, so specifying energy in this way requires knowledge of the nominal voltage of the battery in order to be meaningful.

The fully-charged, 12 V, 80 Ah battery is used to drive a motorized hoist to lift a 150 lb person into the air. The electromechanical energy conversion process, accounting for battery, motor, and mechanical losses, has an efficiency of 85%.

Required:
a. If the battery is fully-discharged during the lifting process, how high can the person be lifted? Assume constant battery voltage and no height limitation on the hoist.
b. The maximum allowable battery current is 15 A. How long will it take to lift the person to the height determined in part a?
c. What is the battery's output power during the lift? You may assume that the battery voltage remains constant.

Answers

Answer 1

Answer:

a)   4401.7 m

b)  5.3 hours

c) 180 watts

Explanation:

a) Determine how high a person can be lifted

since energy = voltage * amperes

                     = 12v * 80Ah = 960 watt h

960 watt h ≈ 960 * 3600 J

                  = 3456 KJ

next we will calculate the gravitational potential energy

Gpe = mass of person * g * h

       = (150*0.454)kg * 9.8 * h

Gpe  = 667.38 * h  ------ ( 1 )

since efficiency is = 85% = 0.85

E (out ) from machine = energy * efficiency ------ ( 2 )

                                    = 3456 * 0.85 = 2937.6 KJ  

To determine (h) equate equation 1 and equation 2

667.38 * h = 2937.6 KJ

h = 2937.6 / 667.38

  = 4401.7 m

b) Time taken to reach the height in part A

Eout = Gpe

Eout = ( 12v * 15A * x * 3600J * 0.85 )

Gpe  = 667.38 * h = 667.38 * 4401.7 = 2937606.55

during the lift : 550800 x = 2937606.55

time taken  x = 5.3 hours

c) Determine battery output power during lift

15A * 12v

= 180 watts

Related Questions

Harlin is designing a new car engine that does not create pollution. Which technological design factor is probably the most
important for his design?
OA.
appearance
ОВ.
how easy it is to drive
OC.
environmental impact
OD.
cost

Answers

Answer: environmental impact

Explanation:

From the question, we are informed that Harlin is designing a new car engine that does not create pollution.

The technological design factor which is probably the most important for the design is the impact on the environment.

Pollution has a negative effect on the environment a d doing this shows that emphasis is placed on how the environmental issue of pollution can be tackled.

Suppose your bathroom sink is clogged and you have decided to try and unclog it by pushing a wire into the drain. You have several types of wire available around the house, some insulated and some not. Which of the following wire characteristics would you need to consider in selecting a wire for the job?

The wire characteristics are listed as follows:

a. Immunity to electrical noise
b. Color of the insulation
c. Resistance of the insulation to salt water
d. Resistance of the insulation to fire
e. Cost
f. Stiffness
g. Ease of stripping the insulation -
h. Weight
i. Availability
j. Strength
k. Resistance to high temperatures
l. Resistance to stretching

Answers

Answer:

stiffness ( f )

weight ( h )

availability ( i )

strength ( j )

resistance to stretching ( l )

Explanation:

The wire characteristics to be considered for the job would be the mechanical characteristics only . therefore the characteristics to consider are :

stiffness: since you want to use the wire to unclog the sink it is necessary you consider the flexibility of the wire in order to achieve what you want weight: the lighter the wire the easier it can be used for the jobAvailability : the wire has to be very close and readily available for the job it will be used forStrength: The wire has to be strong enough so that it doesn't break inside the sinkResistance to stretching : The wire needs to have a high ductility

Technician A says that a component may be grounded through its mounting to a major metal part. Technician B says that some components must be grounded by connecting its positive terminal to a metal frame

Answers

Answer:

Technician B is correct

Explanation:

Grounding of component can be done by either connecting its positive  terminal  to a metal frame and then connecting its negative wire to the ground  and not  by mounting it on a major metal part hence Technician B is correct while Technician B is incorrect .

Electrical grounding is an alternate route created to allow excess current entering an equipment to go the ground without destroying the component

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