Which single force acts on an object in freefall?A. Gravity
B. Fluid forces
C. Air resistance
D. Friction

Answers

Answer 1

Answer: It has to be a)gravity

Answer 2

Answer:

gravity is the correct answer

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The diffuser in a jet engine is designed to decrease the kinetic energy of the air entering the engine compressor without any work or heat interactions. Calculate the velocity at the exit of a diffuser when air at 100 kPa and 30°C enters it with a velocity of 357 m/s and the exit state is 200 kPa and 90°C. The specific heat of air at the average temperature of 60°C = 333 K is cp = 1.007 kJ/kg·K.

Answers

Answer:

81.29 m/s

Explanation:

Given:

60°C = 333 K is cp = 1.007 kJ/kg·K.

at air inlet:

Pressure $P_(1)$ = 100 kPa

Temperature $T_(1)$ = 30°C

Velocity $V_(1)$ = 357 m/s

at air outlet:

Pressure $P_(2)$ = 200kPa

Temperature $T_(2)$ = 90°C

We can define the energy balance as:

$E _(in)$ - $E_(out)$ = Δ $E_(system)$ = 0

therefore, $E _(in)$ = $E_(out)$

m $h_(1)$ + m $(V_(1)^(2) )/(2)$ =m $h_(2)$ + $(V_(2)^(2) )/(2)$ (taking m common and cancelling it)

4 $h_(1)$ + $(V_(1)^(2) )/(2)$ = $h_(2)$ + $(V_(2)^(2) )/(2)$

The velocity at the exit of a diffuser:

$V_(2)$ = [ $V_(1)^(2)$ + 2 $c_p{}$ ( $T_(1)$ - $T_(2)$ ) $]^(0.5)$

$V_(2)$ = [ $357^(2)$ + 2 x 1000 x 1.007 x (30-90) $]^(0.5)$

$V_(2)$ = 81.29 m/s

therefore, the velocity at the exit of a diffuser is 81.29 m/s

Answer:

Exit velocity = 498.3m/s

Explanation:

The energy balance for the system is given by:

Ein - Eout = ◇Esystem

Ein = Eout

Therefore

m' (h1 + V1^2/2) = m' (h2 + V2^2/2)

h1 + V1^2/2 = h2 + V2^2/2

The exit velocity will be:

V2 = [V1^2 + 2(h1 - h2)^0.5 = [V1^2 + 2(cp(T1 - T2)]^0.5

But cp = 1.007kJ/kg

V2 = [(357)^2 + 2(1.007)(90-30)(1000m^2/s^2)]^0.5

V2 = [127449 + 120840]^0.5

V2 = [248289]^0.5

V2 = 498.3m/s

A train starting from a distance of velocity of 90 km.h-1 in 10 minutes assuming that the acceleration is uniform find the acceleration and the distance travelled by the train for attending the velocity

Answers

To make this problem solvable and you can get the help you need, I'll complete and arrange some data.

Answer:

Acceleration: $0.0417\ m/s^2$ , Distance=7,500 m

Explanation:

Uniform Acceleration Motion

It's a type of motion in which the velocity of an object changes uniformly over time.

Being a the constant acceleration, vo the initial speed, vf the final speed, and t the time, the following relation applies:

$v_f=v_o+at\qquad\qquad [1]$

The distance traveled by the object is given by:

$\displaystyle x=v_o.t+(a.t^2)/(2)\qquad\qquad [2]$

Using the equation [1] we can solve for a:

$\displaystyle a=(v_f-v_o)/(t)\qquad\qquad [3]$

The problem will be rewritten as follows:

A train starting from rest reaches a velocity of 90 km/h in 10 minutes. Assuming that the acceleration is uniform, find the acceleration and the distance traveled by the train for attending the velocity.

Let's take the relevant data:

vo=0

vf=90 Km/h*1000/3600 = 25 m/s

t = 10 minutes = 10*60 = 600 seconds

Now compute the acceleration by using [3]:

$\displaystyle a=(25-0)/(600)=0.0417$

$a=0.0417\ m/s^2$

Finally, compute the distance:

$\displaystyle x=0*600+(0.0417\cdot 600^2)/(2)$

$x=7,500\ m$

Note: We used the value of the acceleration with more precision than shown.

Acceleration: $\mathbf{0.0417\ m/s^2}$ , Distance=7,500 m

Explain how changes in weather are caused by the interaction of air masses

Answers

When the lower air pressure gets colds it turns to be cold weather turns in to the high pressure like wise it would be changing of high pressure gets change in to the low pressure of it.So that there will be huge storm has been occurred and it will cause a rain.

Frequency could be measured using which quantity?a. meters
b. seconds
c. waves per second
d. meters per second

Answers

Frequency is the amount kf waves that pass a certain point jn a given amount of time- so the answer is c

The __________ is the layer of the atmosphere where satellites and the space shuttle orbit the Earth.a. troposphere
c. mesosphere
b. stratosphere
d. exosphere

Answers

Answer: d. exosphere

The exosphere is the outermost layer of the atmosphere of earth. It is present above the thermosphere which is lying above the earth. From this layer, the atoms and molecules escape out, which maintains an environment for the movement of satellites and space shuttles.

The most likely answer, according to an informational article I have read, on the earths atmosphere, is exosphere. Hope it helps! If u need more info, message me!

The Cenozoic Era is best described as the era in which