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3 years ago

11

Which term defines the amount of mechanical work an engine can do per unit of heat energy it uses? A. specific heat B. conductiv

ity C. thermal expansion D. efficiency

1 answer:

KengaRu [80]3 years ago

4 0

Answer:

Efficiency

Explanation:

The amount of mechanical work an engine can do per unit of heat energy it uses is called its efficiency.
It is also defined as the output divided by the total electrical power consumed.
In terms of heat, efficiency of engine is given by :

$\eta=1-\dfrac{Q_o}{Q_i}$

$Q_o\ and\ Q_i$ are output heat and input heat respectively.

Hence, the correct option is (d) "efficiency"

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To practice Problem-Solving Strategy 15.1 Mechanical Waves. Waves on a string are described by the following general equation y(

NeX [460]

Answer:

The transverse displacement is $y(1.51 , 0.150) = 0.055 m$

Explanation:

From the question we are told that

The generally equation for the mechanical wave is

$y(x,t) = Acos (kx -wt)$

The speed of the transverse wave is $v = 8.25 \ m/s$

The amplitude of the transverse wave is $A = 5.50 *10^{-2} m$

The wavelength of the transverse wave is $\lambda = 0540 m$

At t= 0.150s , x = 1.51 m

The angular frequency of the wave is mathematically represented as

$w = vk$

Substituting values

$w = 8.25 * 11.64$

$w = 96.03 \ rad/s$

The propagation constant k is mathematically represented as

$k = \frac{2 \pi}{\lambda}$

Substituting values

$k = \frac{2 * 3.142}{0. 540}$

$k =11.64 m^{-1}$

Substituting values into the equation for mechanical waves

$y(1.51 , 0.150) = (5.50*10^{-2} ) cos ((11.64 * 1.151 ) - (96.03 * 0.150))$

$y(1.51 , 0.150) = 0.055 m$

4 0

3 years ago

Q 24, 25, 26 i dont get them and need answers for it

Alexandra [31]

Answer:

24) W = 75 [J]; 25) W = 1794[J]; 26) n = 8.8 (times) or 9 (times)

Explanation:

24) This problem can be solved by means of the following equation.

$DU = Q-W\\$

where:

DU = internal energy difference [J]

Q = Heat transfer [J]

W = work [J]

Since there are no temperature changes the internal energy change is equal to zero

DU = 0

therefore:

$Q = W\\$

The work is equal to the heat transfered, W = 75 [J].

25) The heat transfer can be calculated by means of the following equation.

$Q = m*c_{p}*DT\\where:\\m = mass = 0.4[kg]\\c_{p} = specific heat = 897[J/kg*K]\\DT= 5 [C]$

Q = 0.4*897*5 = 1794[J]

Work is equal to heat transfer, W = 1794[J]

26) Each time the bag falls the potential energy is transformed into heat energy, which is released into the environment. In this way the potential energy is equal to the developed heat.

$E_{p}=Q\\\\E_{p}=m*g*h$

where:

m = mass = 0.5[kg]

g = gravity = 9.81[m/s^2]

h = 1.5 [m]

$E_{p}=0.5*9.81*1.5\\E_{p}=7.36[J]$

The heat developed can be calculated by means of the following equation.

$Q=m*c_{p}*DT\\Q=0.5*130*1\\Q=65[J]$

The number of times will be calculated as follows

n = 65/7.36

n = 8.8 (times) or 9 (times)

7 0

3 years ago

If a battery causes a wire to carry a current of 4 Amps how many coulombs of charge flow past any point in the wire in 3 seconds

BabaBlast [244]

$▪▪▪▪▪▪▪▪▪▪▪▪▪ {\huge\mathfrak{Answer}}▪▪▪▪▪▪▪▪▪▪▪▪▪▪$

According to above question ~

Current (I) = 4 Amperes

Time (t) = 3 seconds

Charge (q) = ?

Let's find the charge (q) by using formula ~

$I = \dfrac{q}{t}$

$4 = \dfrac{q}{3}$

$q = 4 \times 3$

$q = 12 \: \: coulombs$

Hence, 12 coulombs of charge flow past any point in the wire in 3 seconds

7 0

3 years ago

An archer defending a castle is on a 15.5 m high wall. He shoots an arrow straight down at 22.8 m/s. How much time does it take

vazorg [7]

Answer: 1.907

Explanation:

I did the math

3 0

3 years ago

Calculate the current in a circuit when the voltage of the circuit is 5 V and the circuit has a total resistance of 5 Ω.

seropon [69]

the answer is 1a as rearrange gives I = v divided by r

8 0

3 years ago