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vitfil [10]
3 years ago
14

The highly exothermic thermite reaction, in which aluminum reduces iron(iii) oxide to elemental iron, has been used by railroad

repair crews to weld rails together. 2al(s) + fe2o3(s)  2fe(s) + al2o3(s) h = –850 kj what mass of iron is formed when 725 kj of heat are released?
Physics
1 answer:
trapecia [35]3 years ago
6 0

Answer:

To illustrate clearly, I will rewrite the reaction in a more understandable manner.

2 Al(s) +  Fe₂O₃ (s) ⇒ 2 Fe(s) + Al₂O₃(s)                Δhrxn = –850 kJ

This reaction has a negative sign for the change in enthalpy of reaction. The sign convention only means that the reaction releases energy to the surroundings. In other words, the reaction is exothermic. Focusing on only its magnitude, this means that 850 kJ of energy is needed for this reaction of 2 Aluminum moles and 1 mole of Fe₂O₃  to occur. 

Now, if you only had an energy of 725 kJ, then the reaction is incomplete but it will still form Iron (Fe). We use stoichiometric calculations as follows:

725 kJ * (2 mol Fe/850 kJ) = 1.7 moles of Fe

Knowing that the molar mass of Fe is 55.6 g/mol, then the mass of produced iron is

1.7 mol Fe * 55.6 g/mol = 94.85 g iron

Explanation:

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After driving a portion of the route, the taptap is fully loaded with a total of 27 people including the driver, with an average
belka [17]

We will define the Total mass to calculate the force, so our values are:M_p = 69*27=1823Kg\\M_g=15*3=45Kg\\M_c=3*5=15Kg\\M_B=25Kg

Total Mass = 1863+45+15+25=1948Kg

The Weight is,

F=mg=1948*98=19090.4N

Through the hook's Law we calculate X.

F_s=Kx, where x is the lenght of compression and K the Spring constant.

We don't have a K-Spring, but we can assume a random value (or simply let the equation in function of K)

X = \frac{F_s}{x} \\X = \frac{1909.4}{k}

I assume a value of K=4*10^4N/m

X= \frac{1909.4}{4*10^4} = 0.48m

6 0
3 years ago
Technician A says that the governor is used to measure vehicle speed in a hydraulically-controlled automatic transmission. Techn
igor_vitrenko [27]

Answer:

Both technicians are correct

Explanation:

In automobiles, governors are being used. Governors are also known for speed limiters as they can regulate and measure the speed of the automobile.

Hydraulic Transmission: Shifting is controlled by mechanical sensors according to vehicle speed and throttle position/manifold vacuum through valving operated by hydraulic 'pilot' signals.

Electronic Transmission: Shifting is controlled by an on-board computer that receives signals from electronic sensors.

3 0
3 years ago
Plz answer this very soon
tester [92]

Answer:

Im gonna say it is answer A:) Hope this helps!

Explanation:

6 0
3 years ago
Read 2 more answers
You have a two-wheel trailer that you pull behind your ATV. Two children with a combined mass of 76.2 kg hop on board for a ride
marin [14]

a) The spring constant is 12,103 N/m

b) The mass of the trailer 2,678 kg

c) The frequency of oscillation is 0.478 Hz

d) The time taken for 10 oscillations is 20.9 s

Explanation:

a)

When the two children jumps on board of the trailer, the two springs compresses by a certain amount

\Delta x = 6.17 cm = 0.0617 m

Since the system is then in equilibrium, the restoring force of the two-spring system must be equal to the weight of the children, so we can write:

2mg = k'\Delta x (1)

where

m = 76.2 kg is the mass of each children

g=9.8 m/s^2 is the acceleration of gravity

k' is the equivalent spring constant of the 2-spring system

For two springs in parallel each with constant k,

k'=k+k=2k

Substituting into (1) and solving for k, we find:

2mg=2k\Delta x\\k=\frac{mg}{\Delta x}=\frac{(76.2)(9.8)}{0.0617}=12,103 N/m

b)

The period of the oscillating system is given by

T=2\pi \sqrt{\frac{m}{k'}}

where

And for the system in the problem, we know that

T = 2.09 s is the period of oscillation

m is the mass of the trailer

k'=2k=2(12,103)=24,206 N/m is the equivalent spring constant of the system

Solving the equation for m, we find the mass of the trailer:

m=(\frac{T}{2\pi})^2 k'=(\frac{2.09}{2\pi})^2 (24,206)=2,678 kg

c)

The frequency of oscillation of a spring-mass system is equal to the reciprocal of the period, therefore:

f=\frac{1}{T}

where

f is the frequency

T is the period

In  this problem, we have

T = 2.09 s is the period

Therefore, the frequency of oscillation is

f=\frac{1}{2.09}=0.478 Hz

d)

The period of the system is

T = 2.09 s

And this time is the time it takes for the trailer to complete one oscillation.

In this case, we want to find the time it takes for the trailer to complete 10 oscillations (bouncing up and down 10 times). Therefore, the time taken will be the period of oscillation multiplied by 10.

Therefore, the time needed for 10 oscillations is:

t=10T=10(2.09)=20.9 s

#LearnwithBrainly

7 0
3 years ago
A particle accelerator fires a proton into a region with a magnetic field that points in the +x-direction (a) If the proton is m
pochemuha

Answer:

a) -z direction, b) +z direction, c) F=0  

Explanation:

The magnetic force is given by the expression

        F = q v x B

the bold indicate vectors, this equation can be separated in its module

        F = a v B sin θ

and where θ is the angles between the speed and the magnetic field.

The direction of the force can be found with the right-hand rule. For a positive charge, the thumb goes in the direction of speed, the fingers extended in the direction of the magnetic field and the palm points in the direction of the force, if the charge is negative the force is in the opposite direction.

a) Let's apply this to our case

the proton is positively charged

moves in the direction of + x

The magnetized field goes in the direction of y

therefore applying the right hand rule the force must be in the direction of the negative part of the z-axis (-z)

The right-hand rule is used to find this address.

b)  in this case it indicates that the proton moves in the recode of -y

again we apply the right hand rule and the force is in the direction of + z

c)   The proton moves in the x direction

In this case the force is zero because the angle between the field and the speed is zero and the sine is zero, therefore the force is zero

4 0
3 years ago
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