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3 years ago

In Physics, work depends on two factors. What are those two factors?

Physics

1 answer:

Aloiza [94]3 years ago

5 0

Answer:

Force and displacement.

Explanation:

Work done is positive when we push table and it move in the direction of applied force.

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(a) What is the cost of heating a hot tub containing 1440 kg of water from 10.0°C to 40.0°C, assuming 75.0% efficiency to take h

BaLLatris [955]

Answer:

a) $E = 6.024\,USD$ , For m kilograms, it is 4184m J., 3600000 joules, b) $i = 88.200\,A$

Explanation:

a) The amount of heat needed to warm water is given by the following expression:

$Q_{needed} = m_{w}\cdot c_{w}\cdot (T_{f}-T_{i})$

Where:

$m_{w}$ - Mass of water, measured in kilograms.

$c_{w}$ - Specific heat of water, measured in $\frac{J}{kg\cdot ^{\circ}C}$ .

$T_{f}$ , $T_{i}$ - Initial and final temperatures, measured in $^{\circ}C$ .

Then,

$Q_{needed} = (1440\,kg)\cdot \left(4184\,\frac{J}{kg\cdot ^{\circ}C} \right)\cdot (40^{\circ}C - 10^{\circ}C)$

$Q_{needed} = 180748800\,J$

The energy needed in kilowatt-hours is:

$Q_{needed} = 180748800\,J\times \left(\frac{1}{3600000}\,\frac{kWh}{J} \right)$

$Q_{needed} = 50.208\,kWh$

The electric energy required to heat up the water is:

$E = \frac{50.208\,kWh}{0.75}$

$E = 66.944\,kWh$

Lastly, the cost of heating a hot tub is: (USD - US dollars)

$E = (66.944\,kWh)\cdot \left(0.09\,\frac{USD}{kWh} \right)$

$E = 6.024\,USD$

The heat needed to raise the temperature a degree of a kilogram of water is 4184 J. For m kilograms, it is 4184m J. Besides, a kilowatt-hour is equal to 3600000 joules.

b) The current required for the electric heater is:

$i = \frac{Q_{needed}}{\eta \cdot \Delta V \cdot \Delta t}$

$i = \frac{180748800\,J}{0.75\cdot (220\,V)\cdot (3.45\,h)\cdot \left(3600\,\frac{s}{h} \right)}$

$i = 88.200\,A$

7 0

3 years ago

A human being can be electrocuted if a current as small as 51.0 ma passes near the heart. an electrician working with sweaty han

boyakko [2]

The fatal current is 51 mA = 0.051 Ampere.

The resistance is 2,050Ω .

Voltage = (current) x (resistance)

= (0.051 Ampere) x (2,050 Ω) = 104.6 volts .

==================

This is what the arithmetic says IF the information in the question
is correct.

I don't know how true this is, and I certainly don't plan to test it,
but I have read that a current as small as  15 mA  through the
heart can be fatal, not  51 mA .

If 15 mA can do it, and the sweaty electrician's resistance is
really 2,050 Ω, then the fatal voltage could be as little as  31 volts !

The voltage at the wall-outlets in your house is 120 volts in the USA !
THAT's why you don't want to stick paper clips or a screwdriver into
outlets, and why you want to cover unused outlets with plastic plugs
if there are babies crawling around.

6 0

3 years ago

When we learn new information, we often change

EastWind [94]

The data from our experiment.

3 0

3 years ago

Read 2 more answers

Which statement describes the law of conservation of energy?

dmitriy555 [2]

Answer:

Explanation: