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3 years ago

When a rocket lifts off what provides the momentum match of the upper lift

1 answer:

5 0

The momentum of the mass expelled in the opposite direction ... the rocket-engine exhaust, or the ionized matter expelled from an ion drive.

THAT's why every propulsion engine has outlet nozzles designed with super-high-intensity math, to achieve the highest possible velocity for the mass that gets shot out the back ... so that it will carry the maximum possible momentum.

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A tank having a volume of 0.85 m 3 initially contains water as a two-phase liquid-vapor mixture at 260 o C and a quality of 0.7.

Keith_Richards [23]

Answer:=14,160 kJ

Explanation: Let m1 and m2 be the initial and final amounts of mass within the tank, respectively. The steam properties are listed in the table below

Specific Internal SpecificTemp Pressure Volume Energy Enthalpy Quality Phase

C MPa m^3/kg kJ/kg kJ/kg

1 260 4.689 0.02993 2158 2298 0.7 Liquid Vapor Mixture

2 260 4.689 0.0422 2599 2797 1 Saturated Vapor

The mass initially contained in the tank is m1 = V/v1

m1 =0.85 m^3 /0.02993 m^3 /kg

= 28.4 kg

The mass finally contained in the tank is

m2 =V2/v

= 0.85 m^3 /0.0422 m^3 /kg

= 20.14 kg

The heat transfer is then

Qcv = m2u2 − m1u1 − he(m2 − m1)

Qcv = (20.14)(2599) − (28.4)(2158) − (2797)(20.14 − 28.4) = 14,160 kJ

4 0

3 years ago

A certain radioactive nuclide decays with a disintegration constant of 0.0178 h-1.

umka21 [38]

Explanation:

Given that,

The disintegration constant of the nuclide, $\lambda=0.0178\ h^{-1}$

(a) The half life of this nuclide is given by :

$t_{1/2}=\dfrac{ln(2)}{\lambda}$

$t_{1/2}=\dfrac{ln(2)}{0.0178}$

$t_{1/2}=38.94\ h$

(b) The decay equation of any radioactive nuclide is given by :

$N=N_oe^{-\lambda t}$

$\dfrac{N}{N_o}=e^{-\lambda t}$

Number of remaining sample in 4.44 half lives is :

$t_{1/2}=4.44\times 38.94$

$t_{1/2}=172.89\ h^{-1}$

So, $\dfrac{N}{N_o}=e^{-0.0178\times 172.89}$

$\dfrac{N}{N_o}=0.046$

$t_{1/2}=14.6\times 24$

$t_{1/2}=350.4\ h^{-1}$

So, $\dfrac{N}{N_o}=e^{-0.0178\times 350.4}$

$\dfrac{N}{N_o}=0.0019$

Hence, this is the required solution.

4 0

3 years ago

The froghopper Philaenus spumarius is supposedly the best jumper in the animal kingdom. To start a jump, this insect can acceler

Kay [80]

Answer:

Part a)

$v_f = 4 m/s$

Part b)

$t = 0.001 s$

Part c)

$d = 0.815 m$

Explanation:

Part a)

As we know that initially the grass hopper is at rest at the ground position

Now the acceleration is given as

$a = 4000 m/s^2$

distance of the legs that it stretched is given as

$s = 2.0 mm$

so we have

$v_f^2 - v_i^2 = 2 a d$

$v_f^2 - 0 = 2(4000)(0.002)$

$v_f = 4 m/s$

Part b)

time taken to reach this speed is given as

$v_f - v_i = at$

$4 - 0 = 4000 t$

$t = 0.001 s$

Part c)

as the grass hopper reach the maximum height its final speed would be zero

so we will have

$v_f^2 - v_i^2 = 2 a d$

$0 - 4^2 = 2(-9.81) d$

$d = 0.815 m$

5 0

3 years ago

Why is the earth's magnetic field important for us?

Nataly_w [17]

It protects us from the magnetic/electrical radiation that comes from the sun. High radiation periods coincide with solar storms.

8 0

3 years ago

38.You walk from your house to the store 1.0 km in 25 minutes, and then you spent 10 minutes in the store. In your way back home

borishaifa [10]

Answer:

0.24 km

Explanation:

Total time taken = 25 + 10 + 15 = 50 mins

Total distance covered = 1.0 km( initial distance ) + 0.76 km( final distance ) = 1.76 km

therefore the displacement of the individual = 1 - 0.76 = 0.24 km

displacement is the difference between final distance and initial distance covered by an individual and it is a vector quantity

7 0

3 years ago