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vfiekz [6]
3 years ago
14

If a system has 225 kcal of work done to it, and releases 5.00 × 102 kj of heat into its surroundings, what is the change in int

ernal energy of the system?
Physics
1 answer:
vovikov84 [41]3 years ago
8 0

We can solve the problem by using the first law of thermodynamics:

\Delta U = Q-W

where

\Delta U is the change in internal energy of the system

Q is the heat absorbed by the system

W is the work done by the system on the surrounding


In this problem, the work done by the system is

W=-225 kcal=-941.4 kJ

with a negative sign because the work is done by the surrounding on the system, while the heat absorbed is

Q=-5 \cdot 10^2 kJ=-500 kJ

with a negative sign as well because it is released by the system.


Therefore, by using the initial equation, we find

\Delta U=Q-W=-500 kJ+941.4 kJ=441.4 kJ

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asambeis [7]

Answer:

I=0.0987kg.m^2

Explanation:

From the question we are told that:

Mass M=1.80kg

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Time t=0.940s

Generally the equation for moment of inertia is mathematically given by

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 I=\frac{0.94}{2.3.142}^2(1.80*9.8*0.250)

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3 years ago
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3 years ago
What evidence indicates that a chemical change took place when the iron and sulfur combined to form iron sulfide? A. The element
fgiga [73]

Answer:

Explanation:burn the gas

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3 years ago
Read 2 more answers
3.
ratelena [41]

Answer:

1.84 kJ  (kilojoules)

Explanation:

A specific heat of 0.46 J/g Cº means that it takes 0.46 Joules of energy to raise the temperature of 1 gram of iron by 1 Cº.

If we want to heat 50 g of iron from 20° C to 100° C, we can make the following calculation:

Heat = (specific heat)*(mass)*(temp change)

Heat = (0.46 J/g Cº)*(50g)*(100° C -  20° C)

[Note how the units cancel to yield just Joules]

Heat = 1840 Joules, or 1.84 kJ

[Note that the number is positive:  Energy is added to the system.  If we used cold iron to cool 50g of 100° C water, the temperature change would be (Final - Initial) or (20° C - 100° C).  The number is -1.84 kJ:  the negative means heat was removed from the system (the iron).

8 0
2 years ago
Three bullets are fired simultaneously by three guns aimed toward the center of a circle where they mash into a stationary lump.
earnstyle [38]

Answer:

2,87 * 10^{-3}

Explanation:

When the bullets meet at the center and collide, since momentum is a vectoral quantity, their momentum vectors even up and are sumof zero. Formula of momentum is P = m.v , where m is mass and v is velocity. Let’s name the first two bullets as x,y and the one which mass is unknown as z. Then calculate momentum of x and y:

Px= 5,30 * 10^{-3} * 301 = 1,5953 kg*m/s

Py= 5,30 * 10^{-3} * 301 = 1,5953 kg*m/s

The angle between x and y bullets is 120°, and we know that if the angle between two equal magnitude vectors is 120°, the magnitude of the resultant vector will be equal to first two and placed in exact middle of two vectors. So we can say total momentum of x and y (Px+Py) equals to 1,5953 kg*m/s as well (Shown in the figure).  

For z bullet to equalize the total momentum of x and y bullets, it needs to have the same amount of momentum in the opposite way.

Pz = 1,5953 = m * 554

m = 2,87 * 10^{-3} kg

8 0
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