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LuckyWell [14K]

2 years ago

13

An internal combustion engine in which air is compressed to a high enough pressure and temperature that combustion occurs when f

uel is injected is called a(n) -ignition engine.

1 answer:

pashok25 [27]2 years ago

3 0

Answer:

Spark

Explanation

The spark plug fires igniting the fuel. In diesel trucks the air is compressed until ignition.

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______number can be used to describe the relative growth of the hydraulic boundary layer and the thermal boundary layer. a) Reyn

weqwewe [10]

Answer: d) Prandtl number

Explanation: Prandtl number is basically defined as the ratio between the fluid's viscosity to the thermal conductivity.It doesn't have any sort of dimension. The fluids which are discovered with the small Prandtl numbers are considered as good fluids as they have a smooth rate of flow and as the number increases the fluid are not considered as reliable. Thus,option (d) is the correct option.

3 0

4 years ago

A 220-V electric heater has two heating coils that can be switched such that either coil can be used independently or the two ca

Nana76 [90]

Answer:

The resistances of both coils are 131.7 Ω and 29.64 Ω.

Explanation:

Since, there are two coils, they can be used independently or in series or parallel. The power is given as:

Power = P = VI

but, from Ohm's Law:

V = IR

I = V/R

therefore,

P = V²/R

R = V²/P

Hence, the resistance (R) and (P) are inversely proportional. Therefore, the maximum value of resistance will give minimum power, that is, 300 W. And the maximum resistance will be in series arrangement, as in series the total resistance gets higher than, any individual resistance.

Therefore,

Rmax = V²/Pmin = R1 + R2

R1 + R2 = (220 V)²/300 W

R1 + R2 = 161.333 Ω ______ en (1)

Similarly, the minimum resistance will give maximum power. And the minimum resistance will occur in parallel combination. Because equivalent resistance of parallel combination is less than any individual resistance.

Therefore,

(R1 R2)/(R1 + R2) = (220 V)²/2000 W

using eqn (1), we get:

(R1 R2) / 161.333 Ω = 24.2 Ω

R1 R2 = 3904.266 Ω²

R1 = 3904.266 Ω²/R2 _____ eqn (2)

Using this value of R1 in eqn (1), we get:

3904.266/R2 +R2 = 161.333

(R2)² - 161.333 R2 +3904.266 = 0

Solving this quadratic eqn we get two values of R2 as:

R2 = 131.7 Ω OR R2 = 29.64 Ω

when ,we substitute these values in eqn (1) to find R1, we get get the same two values as R2, alternatively. This means that the two coils have these resistance, and the order does not matter.

<u>Therefore, the resistance of both coils are found to be 131.7 Ω and 29.64 Ω</u>

7 0

3 years ago

If you touch a downed power line, covered or bare, what's the likely outcome?

muminat

You are going to die most likely from being electrocuted

5 0

3 years ago

An automobile engine provides 632 Joules of work to push the pistons and generates 2203 Joules of heat that must be carried away

Ronch [10]

Answer:

The change in internal energy of the engine is -1,571 Joules.

Explanation:

Change in internal energy (∆U) = energy output (U2) - energy generated (U1)

U1 is the energy generated = 2203 Joules

U2 is the energy output = 632 Joules

Change in internal energy (∆U) = 632 - 2203 = -1,571 Joules

3 0

3 years ago

Read 2 more answers

A particle is placed motionless at a point 12m to the right of the origin. Its acceleration as a function of time is a = -30 + 3

kondor19780726 [428]

Answer:

$x(t)=-15t^2+5t^3+12$

Explanation:

To find the expression for the position x of the particle as a function of time t you need to integrate the expression for acceleration two times. To find the integral constants you are already given the initial conditions for both the position and the velocity which are:

$x(t=0)=12\\v(t=0)=0$

The first integration gives you the velocity:

$v(t)=\int a(t) dt=-30t+15t^2+C_1$

You get the constant by using the second initial condition:

$C_1=0$

To get the expression for the position you need to integrate again:

$x(t)=\int v(t)dt=-15t^2+5t^3+C_2$

where $C_2=12\\$ using the first initial condition.

You can now plot the graph. To get the total distance travelled you can integrate the expression for the velocity twice and sum the two integrals (from 0 to 1 and from 1 to 3):

$\int_0^1|v(t)|dt+\int_1^3|v(t)|dt=$ 20 m

3 0

4 years ago

Read 2 more answers