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3 years ago

A book with a mass of 1.2 kg sits on a bookshelf. If it has a gravitational

Physics

1 answer:

Andreyy893 years ago

6 0

I'm sorry, I just saw this. I hope I'm not too late.

GPE = mass * gravity * height

height = GPE/(mass * gravity)

height = 50/(1/2 * 9.8)

height = 10.2041 Meters

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An electric bell is placed inside a transparent glass jar. The bell can be turned on and off using a switch on the outside of th

Art [367]

The answer is : We’ll see the bell move, but we won’t hear it ring. This is because light can travel through vacuum but sound cannot. Sound waves are vibrations of particles in any media, so sound requires a medium to travel, and it cannot travel in a vacuum as there is no particles to vibrate.

5 0

2 years ago

Read 2 more answers

An ocean thermal energy conversion system is being proposed for electric power generation. Such a system is based on the standar

defon

Answer:

Explanation:

Dear Student, this question is incomplete, and to attempt this question, we have attached the complete copy of the question in the image below. Please, Kindly refer to it when going through the solution to the question.

To objective is to find the:

(i) required heat exchanger area.

(ii) flow rate to be maintained in the evaporator.

Given that:

water temperature = 300 K

At a reasonable depth, the water is cold and its temperature = 280 K

The power output W = 2 MW

Efficiency $\zeta$ = 3%

where;

$\zeta = \dfrac{W_{out}}{Q_{supplied }}$

$Q_{supplied } = \dfrac{2}{0.03} \ MW$

$Q_{supplied } = 66.66 \ MW$

However, from the evaporator, the heat transfer Q can be determined by using the formula:

Q = UA(L MTD)

where;

$LMTD = \dfrac{\Delta T_1 - \Delta T_2}{In (\dfrac{\Delta T_1}{\Delta T_2} )}$

Also;

$\Delta T_1 = T_{h_{in}}- T_{c_{out}} \\ \\ \Delta T_1 = 300 -290 \\ \\ \Delta T_1 = 10 \ K$

$\Delta T_2 = T_{h_{in}}- T_{c_{out}} \\ \\ \Delta T_2 = 292 -290 \\ \\ \Delta T_2 = 2\ K$

$LMTD = \dfrac{10 -2}{In (\dfrac{10}{2} )}$

$LMTD = \dfrac{8}{In (5)}$

LMTD = 4.97

Thus, the required heat exchanger area A is calculated by using the formula:

$Q_H = UA (LMTD)$

where;

U = overall heat coefficient given as 1200 W/m².K

$66.667 \times 10^6 = 1200 \times A \times 4.97 \\ \\ A= \dfrac{66.667 \times 10^6}{1200 \times 4.97} \\ \\ \mathbf{A = 11178.236 \ m^2}$

The mass flow rate:

$Q_{H} = mC_p(T_{in} -T_{out} ) \\ \\ 66.667 \times 10^6= m \times 4.18 (300 -292) \\ \\ m = \dfrac{ 66.667 \times 10^6}{4.18 \times 8} \\ \\ \mathbf{m = 1993630.383 \ kg/s}$

3 0

2 years ago

It is 5.5 km from your home to the physics lab. As part of your physical fitness program, you could run that distance at 10 km/h

stealth61 [152]

Explanation:

Displacement = 5 km

Converting km/h to m/s,

10 km/h * 1000 m/1 km * 1 h/3600 s

= 25/9 m/s

Remember,

700 watt = 700 J/s

Velocity = displacement/time

Time = 5000/(25/9)

= 1800 s

Energy = power * time

= 700 * 1800

= 1,260,000

= 1260 kJ

Converting km/h to m/s,

3 km/h * 1000 m/1 km * 1 h/3600 s

= 5/6 m/s

290 watt = 290 J/s

Velocity = displacement/time

Time = 5000/(5/6)

= 6000 s

Energy = power * time

= 290 * 6000

= 1,740,000

= 1740 kJ

Walking burns more energy; 1,740,000 joules. It burns more because you walk for a greater period of time.

6 0

2 years ago

A substance made of two or more elements is called a what

SSSSS [86.1K]

I think it’s a compound.

8 0

2 years ago

In 2h2so4, the number of hydrogen atoms is 1 2 4 8

pishuonlain [190]

C.) In this, number of Hydrogen atoms is 4

7 0

2 years ago