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3 years ago

A refrigeration cycle has Qout = 1000 Btu and Wcycle = 300 Btu. Determine the coefficient of performance for the cycle.

Physics

1 answer:

DENIUS [597]3 years ago

5 0

Answer:

The coefficient of performance for the cycle is 2.33.

Explanation:

Given that,

Output energy $Q_{out}=1000\ Btu$

Work done $W_{cycle}=300\ Btu$

We need to calculate the coefficient of performance

Using formula of the coefficient of performance

$COP=\dftrac{Q_{in}}{W_{cycle}}$

We need to calculate the $Q_{in}$

$W_{cycle}=Q_{out}-Q_{in}$

Put the value into the formula

$300=1000-Q_{in}$

$Q_{in}=300-1000$

$Q_{in}=700\ Btu$

Now put the value of $Q_{in}$ into the formula of COP

$COP=\dfrac{700}{300}$

$COP=\dfrac{7}{3}=2.33$

Hence, The coefficient of performance for the cycle is 2.33.

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A small mass is released from rest from the edge of a frictionless, hemispherical bowl. As the mass passes through the bottom of

Greeley [361]

Answer:

$a=2g$

Explanation:

Let the radius of the hemisphere is R. The mass is released from rest so the initial speed is equal to zero and acceleration is equal to the g.

By the Newton's 3rd equation,

$v^2=u^2+2as\\v^2=2gR\\v=\sqrt{2gR}$

Now, at the bottom hemisphere the centripetal acceleration will act on the mass and the direction of this force is towards center,

$a_c=\frac{v^2}{R}\\a_c=\frac{(\sqrt{2gR} )^2}{R}\\a_c=2g$

Hence, the acceleration on the bottom of the hemisphere is equal to the 2g.

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3 years ago

Galileo's contribution to the study of motion

N76 [4]

Helped us in modern days do to his contribution to the study of motion back in the day is what helpes us know how to study motion.

6 0

3 years ago

The amount of air resistance acting on an object depends on the objects

alexandr402 [8]

Answer:

Shape of the object

Explanation:

This depends on the shape of the object. For a spherical object, a unitless value of 0.47 is typical. The magnitude of the velocity squared. The faster you go, the greater the air resistance force

7 0

2 years ago

A 50-kg copper block initially at 140Â°c is dropped into an insulated tank that contains 90 l of water at 10Â°c. Determine the f

xxMikexx [17]

Answer:

$T_f=24.71$

Explanation:

From the question we are told that:

Mass of block $m=50$

Temperature of block $T_b =140 \textdegree C$

Volume of water $V= 90L$

Temperature of water $T_w=10 \textdegree C$

Density of water $\rho=1000kg/m^3$

Specific heat of water $C_w=4.18KJ/kg-k$

Specific heat of copper $C_p=0.96KJ/kg-k$

Generally the equation for equilibrium stage is mathematically given by

$mC_p(T_b-T_f)=\rho*VV*c(T_f-T_w)$

$50*0.96(140-T_f)=1000*90*10^-3*c_w(T_f-10)$

$48(140-T_f)=376.2(T_f-10)$

$140-T_f=7.8375(T_f-10)$

$140-T_f=7.8375T_f-78.375$

$-8.8375T_f=-218.375$

$T_f=\frac{-218.375}{-8.8375}$

$T_f=24.71$

6 0

3 years ago

A pendulum has 294 J of potential energy at the highest point of its swing. How much kinetic energy will it have at the bottom o

baherus [9]

Newton's law of conservation states that energy of an isolated system remains a constant. It can neither be created nor destroyed but can be transformed from one form to the other.

Implying the above law of conservation of energy in the case of pendulum we can conclude that at the bottom of the swing the entire potential energy gets converted to kinetic energy. Also the potential energy is zero at this point.

Mathematically also potential energy is represented as

Potential energy= mgh

Where m is the mass of the pendulum.

g is the acceleration due to gravity

h is the height from the bottom z the ground.

At the bottom of the swing,the height is zero, hence the potential energy is also zero.

The kinetic energy is represented mathematically as

Kinetic energy= 1/2 mv^2

Where m is the mass of the pendulum

v is the velocity of the pendulum

At the bottom the pendulum has the maximum velocity. Hence the kinetic energy is maximum at the bottom.

Energy can neither be created e destroyed. It can only be transferred from one form to another. Implying this law and the above explainations we conclude that at the bottom of the pendulum,the potential energy=0 and the kinetic energy=294J as the entire potential energy is converted to kinetic energy at the bottom.

6 0

3 years ago