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3 years ago

1. As a swimmer jumps off a 10.0 m high diving board, they start to accelerate towards the

Physics

1 answer:

stich3 [128]3 years ago

6 0

Answer:

1960 J

Explanation:

Potential energy is given as the product of mass, height and acceleration due to gravity and expressed as mgh where m represent the mass of the swimmer, g is acceleration due to gravity and h is the height. Since the swimmer has just gone 4 m from the surface, that is the height that potential energy is converted to kinetic energy. This follows the law of transformation of energy since the energy can't be lost but rather transformed from one state to another. Therefore, substituting 50 kg for m, 4 m for h and 9.8 for g we obtain that PE=50*4*9.8=1960 J. Since it's not among the options here, maybe it is option D

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Steam is to be condensed on the shell side of a heat exchanger at 150 oF. Cooling water enters the tubes at 60 oF at a rate of 4

zalisa [80]

Answer:

a. 572Btu/s

b.0.1483Btu/s.R

Explanation:

a.Assume a steady state operation, KE and PE are both neglected and fluids properties are constant.

From table A-3E, the specific heat of water is $c_p=1.0\ Btu/lbm.F$ , and the steam properties as, A-4E:

$h_{fg}=1007.8Btu/lbm, s_{fg}=1.6529Btu/lbm.R$

Using the energy balance for the system:

$\dot E_{in}-\dot E_{out}=\bigtriangleup \dot E_{sys}=0\\\\\dot E_{in}=\dot E_{out}\\\\\dot Q_{in}+\dot m_{cw}h_1=\dot m_{cw}h_2\\\\\dot Q_{in}=\dot m_{cw}c_p(T_{out}-T_{in})\\\\\dot Q_{in}=44\times 1.0\times (73-60)=572\ Btu/s$

Hence, the rate of heat transfer in the heat exchanger is 572Btu/s

b. Heat gained by the water is equal to the heat lost by the condensing steam.

-The rate of steam condensation is expressed as:

$\dot m_{steam}=\frac{\dot Q}{h_{fg}}\\\\\dot m_{steam}=\frac{572}{1007.8}=0.5676lbm/s$

Entropy generation in the heat exchanger could be defined using the entropy balance on the system:

$\dot S_{in}-\dot S_{out}+\dot S_{gen}=\bigtriangleup \dot S_{sys}\\\\\dot m_1s_1+\dot m_3s_3-\dot m_2s_2-\dot m_4s_4+\dot S_{gen}=0\\\\\dot m_ws_1+\dot m_ss_3-\dot m_ws_2-\dot m_ss_4+\dot S_{gen}=0\\\\\dot S_{gen}=\dot m_w(s_2-s_1)+\dot m_s(s_4-s_3)\\\\\dot S_{gen}=\dot m c_p \ In(\frac{T_2}{T_1})-\dot m_ss_{fg}\\\\\\\dot S_{gen}=4.4\times 1.0\times \ In( {73+460)/(60+460)}-0.5676\times 1.6529\\\\=0.1483\ Btu/s.R$

Hence,the rate of entropy generation in the heat exchanger. is 0.1483Btu/s.R

4 0

3 years ago

Help! How do you find the Eccentricity??

denis23 [38]

Explanation:

The formula to determine the eccentricity of an ellipse is the distance between foci divided by the length of the major axis

8 0

3 years ago

The instruction booklet for your pressure cooker indicates that its highest setting is 12.3 psi . you know that standard atmosph

zmey [24]

<span>118 C The Clausius-Clapeyron equation is useful in calculating the boiling point of a liquid at various pressures. It is: Tb = 1/(1/T0 - R ln(P/P0)/Hvap) where Tb = Temperature boiling R = Ideal Gas Constant (8.3144598 J/(K*mol) ) P = Pressure of interest Hvap = Heat of vaporization of the liquid T0, P0 = Temperature and pressure at a known point. The temperatures are absolute temperatures. We know that water boils at 100C at 14.7 psi. Yes, it's ugly to be mixing metric and imperial units like that. But since we're only interested in relative pressure differences, it's safe enough. So P0 = 14.7 P = 14.7 + 12.3 = 27 T0 = 100 + 273.15 = 373.15 And for water, the heat of vaporization per mole is 40660 J/mol Let's substitute the known values and calculate. Tb = 1/(1/T0 - R ln(P/P0)/Hvap) Tb = 1/(1/373.15 K - 8.3144598 J/(K*mol) ln(27/14.7)/40660 J/mol) Tb = 1/(0.002679887 1/K - 8.3144598 1/K ln(1.836734694)/40660) Tb = 1/(0.002679887 1/K - 8.3144598 1/K 0.607989372/40660) Tb = 1/(0.002679887 1/K - 5.055103194 1/K /40660) Tb = 1/(0.002679887 1/K - 0.000124326 1/K) Tb = 1/(0.002555561 1/K) Tb = 391.3034763 K Tb = 391.3034763 K - 273.15 Tb = 118.1534763 C Rounding to 3 significant figures gives 118 C</span>

3 0

3 years ago

Suppose you were asked to demonstrate electromagnetic induction. Which of the following situations will result in an electric cu

steposvetlana [31]

D. All of the above. When a wire loop is moved or rotated in a magnetic field, there is a change in magnetic flux which produces emf in wire loop and hence electric current is produced.

5 0

3 years ago

Read 2 more answers

Please help me answer the following question!

Troyanec [42]

Answer:

P = 0

Explanation:

Momentum is defined as the quentity of motion contained in a body. Mathematically, it can be defined as the product of mass and velocity. So, in order to determine the Volkswagen Beetle, at rest, we can use the simple formula, as follows:

where,

P = Momentum of Volkswagen Beetle = ?

m = Mass of Volkswagen Beetle = 750 kg

v = Velocity of Volkswagen Beetle = 0 m/s (since, it is at rest)

Therefore,

P =

3 0

2 years ago