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pychu [463]
3 years ago
5

James Joule (after whom the unit of energy is named) claimed that the water at the bottom of Niagara Falls should be warmer than

the water at the top, 51 mm above the bottom. He reasoned that the falling water would transform its gravitational potential energy at the top into thermal energy at the bottom, where turbulence brings the water almost to a halt..
Physics
1 answer:
Y_Kistochka [10]3 years ago
4 0

The complete question is;

James Joule (after whom the unit of energy is named) claimed that the water at the bottom of Niagara Falls should be warmer than the water at the top, 51 m above the bottom. He reasoned that the falling water would transform its gravitational potential energy at the top into thermal energy at the bottom, where turbulence brings the water almost to a halt. If this transformation is the only process occurring, how much warmer will the water at the bottom be?

Answer:

Water becomes warmer by a temperature of ΔT = 0.119 K

Explanation:

If we assume that gravitational kinetic energy will be converyrf into thermal enrgy, we will have;

Q = U

So, m•c_w•ΔT = mgh

Where;

c_w is specific heat capacity of water with a value of 4184 J/Kg.K

ΔT is change in temperature indicating how warmer the water will be. Thus making ΔT the subject, we have;

ΔT = gh/c_w

So, ΔT = 9.8 x 51/4184 = 0.119 K

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A recent home energy bill indicates that a household used 475475 kWh (kilowatt‑hour) of electrical energy and 135135 therms for
faltersainse [42]

Answer:

Explanation:

Given that,.

A house hold power consumption is

475 KWh

Gas used is

135 thermal gas for month

Given that, 1 thermal = 29.3 KWh

Then,

135 thermal = 135 × 29.3 = 3955.5 KWh

So, total power used is

P = 475 + 3955.5

P =4430.5 KWh

Since 1 hr = 3600 seconds

So, the energy consumed for 1hr is

1KW = 1000W

P = energy / time

Energy = Power × time

E = 4430.5 KWhr × 1000W / KW × 3600s / hr

E = 1.595 × 10^10 J

So, using Albert Einstein relativity equation

E = mc²

m = E / c²

c is speed of light = 3 × 10^8 m/s

m = 1.595 × 10^10 / (3 × 10^8)²

m = 1.77 × 10^-7 kg

Then,

1 kg = 10^6 mg

m = 1.77 × 10^-7 kg × 10^6 mg / kg

m = 0.177mg

m ≈ 0.18 mg

5 0
3 years ago
A 100 Kg man is diving off a 50 meter cliff. What is his kinetic energy when he is 20 meters from the water?
iren2701 [21]

Answer:

K.E=29.403125J

Explanation:

From the question we are told that

Mass M=100

Height 50-20=30m

Generally the equation for velocity before impact is is is mathematically given by

v=\sqrt{2gh}

v=\sqrt{2*9.8*30}

v=24.25

Generally the equation for Kinetic Energy is is mathematically given by

K.E=\frac{1}{2}mv^2

K.E=\frac{1}{2}*100*(24.25)^2\\

K.E=29403.125J

K.E=29.403125J

8 0
3 years ago
Telephone signals are often transmitted over long distances by microwaves. What is the frequency of microwave radiation with a w
amm1812

Answer:

1) f= 8.6 GHz

2) t= 0.2 ms

Explanation:

1)

  • Since microwaves are electromagnetic waves, they move at the same speed as the light in vacuum, i.e. 3*10⁸ m/s.
  • There exists a fixed relationship between the frequency (f) , the wavelength (λ) and the propagation speed in any wave, as follows:

        v = \lambda * f (1)

  • Replacing by the givens, and solving for f, we get:

       f =\frac{c}{\lambda} =\frac{3e8m/s}{0.035m} = 8.57e9 Hz (2)

⇒     f = 8.6 Ghz (with two significative figures)

2)

  • Assuming that the microwaves travel at a constant speed in a straight line (behaving like rays) , we can apply the definition of average velocity, as follows:

       v =\frac{d}{t} (3)

       where v= c= speed of light in vacuum = 3*10⁸ m/s

       d= distance between mountaintops = 52 km = 52*10³ m

  • Solving for t, we get:

       t = \frac{d}{c} = \frac{52e3m}{3e8m/s} = 17.3e-5 sec = 0.173e-3 sec = 0.173 ms (4)

       ⇒  t = 0.2 ms (with two significative figures)

6 0
2 years ago
Which of the following statements is false? Group of answer choices Light that is high in energy has a high frequency. The atomi
MArishka [77]

Answer:

The last statement is false.

Explanation:

Photons (Electromagnetic radiation) are released when electrons drop from a higher energy lever to a lower energy level. Therefore the opposite insinuated by the last statement is wrong.

4 0
3 years ago
Guys please helpp!!!!1
Setler79 [48]

Answer:

Position A/Position E

K = E, U = 0

Position B/Position D

K = (1-x)\cdot E, U = x\cdot E, for 0 < x < 1

Position C

K = 0, U = E

Explanation:

Let suppose that ball-Earth system represents a conservative system. By Principle of Energy Conservation, total energy (E) is the sum of gravitational potential energy (U) and translational kinetic energy (K), all measured in joules. In addition, gravitational potential energy is directly proportional to height (h) and translational kinetic energy is directly proportional to the square of velocity.

Besides, gravitational potential energy is increased at the expense of translational kinetric energy. Then, relative amounts at each position are described below:

Position A/Position E

K = E, U = 0

Position B/Position D

K = (1-x)\cdot E, U = x\cdot E, for 0 < x < 1

Position C

K = 0, U = E

3 0
2 years ago
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