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3 years ago

What temperature is required to transfer waste heat to the environment for a heat engine to be 100 percent efficient?

2 answers:

6 0

This can be seen as a trick question because heat engines can typically never be 100 percent efficient. This is due to the presence of inefficiencies such as friction and heat loss to the environment. Even the best heat engines can only go up to around 50% efficiency.

nirvana33 [79]3 years ago

6 0

Answer:

An infinite temperature

Explanation:

The efficiency of an engine is defined as:

$\eta=1 -\frac{T_C}{T_H}$

where

$T_H$ is the temperature at which heat enters the engine

$T_C$ is the temperature of the environment, to which the engine exhausts heat

From the formula, we see that for an engine to be 100% efficient, the fraction

$\frac{T_C}{T_H}$

must be equal to zero. Since the value of $T_C$ is never zero (the temperature is expressed in Kelvin, and the temperature of the environment can never be exactly 0 K), the only possibility for that to occur is that the temperature at which heat enters the engine ( $T_H$ ) is infinite, so that this fraction becomes zero and the efficiency becomes 1.

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A tall cylinder contains 30 cm of water. Oil is carefully poured into the cylinder, where it floats on top of the water, until t

Anastaziya [24]

Answer:

The gauge pressure is $P_g = 2058 \ P_a$

Explanation:

From the question we are told that

The height of the water contained is $h_w = 30 \ cm = 0.3 \ m$

The height of liquid in the cylinder is $h_t = 40 \ cm = 0.4 \ m$

At the bottom of the cylinder the gauge pressure is mathematically represented as

$P_g = P_w + P_o$

Where $P_w$ is the pressure of water which is mathematically represented as

$P_w = \rho_w * g * h_w$

Now $\rho_w$ is the density of water with a constant values of $\rho_w = 1000 \ kg /m^3$

substituting values

$P_w = 1000 * 9.8 * 0.3$

$P_w = 2940 \ Pa$

While $P_o$ is the pressure of oil which is mathematically represented as

$P_o = \rho_o * g * (h_t -h_w )$

Where $\rho _o$ is the density of oil with a constant value

$\rho _o = 900 \ kg / m^3$

substituting values

$P_o = 900 * 9.8 * (0.4 - 0.3)$

$P_o = 882 \ Pa$

Therefore

$P_g = 2940 - 882$

$P_g = 2058 \ P_a$

6 0

3 years ago

When energy from the sun hits the air above

valentina_108 [34]

Answer: C I think.

Explanation:

3 0

3 years ago

A uniform disk with a 25 cm radius swings without friction about a nail through the rim. If it is released from rest from a posi

ValentinkaMS [17]

Answer:

Explanation:

During the swing , the center of mass will go down due to which disc will lose potential energy which will be converted into rotational kinetic energy

mgh = 1/2 I ω² where m is mass of the disc , h is height by which c.m goes down which will be equal to radius of disc , I is moment of inertia of disc about the nail at rim , ω is angular velocity .

mgr = 1/2 x ( 1/2 m r²+ mr²) x ω²

gr = 1/2 x 1/2 r² x ω² + 1/2r² x ω²

g = 1 / 4 x ω² r + 1 / 2 x ω² r

g = 3 x ω² r/ 4

ω² = 4g /3 r

= 4 x 9.8 / 3 x .25

= 52.26

ω = 7.23 rad / s .

6 0

2 years ago

Who invented the wedge simple machine and why?

Lelu [443]

Answer:

Gene Sarazen began to win tournaments in 1935 with a new club he had invented that was specialized for sand play. He is hailed as the inventor of the sand wedge.

Explanation:

A wedge is a triangular shaped tool, and is a portable inclined plane, and one of the six classical simple machines. It can be used to separate two objects or portions of an object, lift up an object, or hold an object in place. It functions by converting a force applied to its blunt end into forces perpendicular (normal) to its inclined surfaces. The mechanical advantage of a wedge is given by the ratio of the length of its slope to its width.[1][2] Although a short wedge with a wide angle may do a job faster, it requires more force than a long wedge with a narrow angle.

The force is applied on a flat, broad surface. This energy is transported to the pointy, sharp end of the wedge, hence the force is transported.

The wedge simply transports energy and collects it to the pointy end, consequently breaking the item. In this way, much pressure is put on a thin area.

3 0

3 years ago

An oscillator consisting of a material point of m = 200g vibrates under the action of an elastic force according to the equation

Debora [2.8K]

Answer:

an oscillator consisting of a material point of m = 200g vibrates under the action of an elastic force according to the equation y = 0.2sin (π / 4 • t + π / 16) (m)

calculate the period and frequency of the oscillation

calculate the speed and acceleration

calculate the Total Energy

8 0

2 years ago