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3 years ago

which symbol in the first law of thermpdynamics represents energy that moves from a hot object to a cooler object?

1 answer:

4 0

The triangle <span>in the first law of thermodynamics, represents energy that moves from a hot object to a cooler object.</span>

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Lol i'm going to fail please help

Novosadov [1.4K]

Answer:

Explanation:

The frequency is 16.0 Hz. That means that 16 of these waves can pass a single point in 1 second. We are given frequency and wavelength. The equation that relates them is

$f=\frac{v}{\lambda}$ where f is frequency, v is velocity, and λ is wavelength. Putting all this together:

$16.0=\frac{v}{97.5}$ and solving for velocity,

v = 16.0(97.5) so

v = 1560 m/s. This wave can travel 1560 meters in a single second!!! Now that we know this velocity, we can use it in a proportion to find our unknown, which is how long, t, it will take to hear this sound 11000m away. (11 km is 11000m):

$\frac{1560m}{1s}=\frac{11000}{t}$ and cross multiply to get

1560t = 11000 so

t = 7.1 seconds

6 0

3 years ago

Your hands get warm by a fire because _____energy is converted into heat energy

MaRussiya [10]

Answer:

Your hands get warm by fire because chemical energy gets converted into heat energy. When the chemical bonds in the wood are released in the air which then mixes with oxygen and emit heat. This is the reason why it is always hot when you go near something that is burning or is up in flames.

Explanation:

4 0

3 years ago

Read 2 more answers

Air enters a turbine operating at steady state with a pressure of 75 Ibf/in.^2, a temperature of 800º R and velocity of 400 ft/s

Arturiano [62]

Answer:

(a) W/m = 49.334 Btu/lb

(b) $\frac{E_{d} }{m}$ = 22.12 Btu/lb

Explanation:

For the given problem, it can be assumed that the system is operating at steady state and the effects of potential energy can be neglected.

(a) Using the thermodynamic table for air.

At the temperature ( $T_{1}$ )of 800 ºR and pressure ( $P_{1}$ ) of 75 Ibf/in.^2, we can deduce that:

Specific enthalpy ( $h_{1}$ ) = 191.81 BTu/lb

Specific entropy ( $s_{1}$ ) = 0.6956 Btu/(lb.ºR)

At the temperature ( $T_{2}$ )of 600 ºR and pressure ( $P_{2}$ ) of 15 Ibf/in.^2, we can deduce that:

Specific enthalpy ( $h_{2}$ ) = 143.47 BTu/lb

Specific entropy ( $s_{2}$ ) = 0.6261 Btu/(lb.ºR)

The work done can be calculated using energy rate equation:

$\frac{W}{m} = \frac{Q}{m} + (h_{1} - h_{2}) + \frac{V_{1}^{2} - V_{2}^{2}}{2}$

Q/m = heat transfer = -2 Btu/lb

$V_{1}$ = 400 ft/s

$V_{2}$ = 100 ft/s

$\frac{W}{m} = -2 + (191.81 - 143.47) + \frac{400^{2} - 100^{2}}{2}*[tex]\frac{1}{2*32.2*778}$ [/tex] = -2 + 48.34 + 29.938 = 49.334 Btu/lb

(b) To calculate the exergy destruction, we will use the equation for exergy rate:

$\frac{E_{d} }{m} = [1-\frac{T_{o} }{T_{b} }](\frac{Q}{m}) - \frac{W}{m} + [(h_{1} - h_{2}) -T_{o}(s_{1} - s_{2}) + \frac{V^{2} _{1} - V_{2} ^{2}}{2}]$

The equation above is further simplified to:

$\frac{Ed}{m} = T_{o}[(s_{2} -s_{1}) - Rln\frac{P_{2} }{P_{1} } - \frac{Q/m}{T_{b} }]$

Using a reference temperature (To) = 500 °R

Average surface temperature (Tb = 620°R

$\frac{Ed}{m} = 500*[(0.6261 -0.6956) - (1.986/28.97)ln\frac{15 }{75 } - \frac{-2}{620}}]$

$\frac{E_{d} }{m}$ = 500*[-0.0695 +0.068688*1.609 +0.003225] = 22.12 Btu/lb

5 0

4 years ago

A block with a mass of 2kg is pushed 20cm and a constant speed up an incline that makes a 40 degree angle with the floor. how mu

Alexxx [7]

work done will be 2.5872 J

Given :

mass of block = 2kg

distance travelled by block = 20cm

angle of inclination = 40°

To Find :

Work done by gravity

Solution :

Gravity is defined as the force that attracts a body towards the earth or towards any other physical body having mass.

work done by gravity is mgh

If θ is the angle made when the body falls, the work done by gravity is given by,

W = m g h cosθ

W = 2 x 9.8 x 0.2 x cos40°

= 2.5872 J

So work done will be 2.5872 J

Learn more about Work done here:

brainly.com/question/25923373

#SPJ4

8 0

2 years ago

"Response to stimulus" refers to

nlexa [21]

I think is reaction
STIMULUS: In physiology, a stimulus is a detectable change in the internal or external environment. When a stimulus is applied to a sensory receptor, it elicits or influences a reflex via stimulus transduction.

6 0

3 years ago