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3 years ago

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A system gains 757 kJ757 kJ of heat, resulting in a change in internal energy of the system equal to +176 kJ.+176 kJ. How much w

ork is done? ????=w= kJkJ Choose the correct statement. Work was done on the system. Work was done by the system.

1 answer:

Alecsey [184]3 years ago

5 0

Answer:

581 kJ, work was done by the system

Explanation:

According to 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 (positive if absorbed, negative if released)

W is the work done by the system (positive if done by the system, negative if done by the surrounding)

In this problem,

$Q=+757 kJ$

$\Delta U = +176 kJ$

Therefore the work done by the system is

$W=Q-\Delta U=757 kJ-176 kJ=+581 kJ$

And the positive sign means the work is done BY the system.

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Calculate the total energy of 4.0 kg object moving horizontally at 20 m/s 50 meters above the surface.

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Answer:

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Explanation:

Given:

m = 4 kg the mass of the object

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E total = ? J

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E total = Ep + Ek

Ep = m g H we take g = 10 m/s²

Ep = 4 · 10 · 50 = 2,000 J

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Ek = 4 · 20² / 2 = 2 · 400 = 800 J

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sleet_krkn [62]

Answer:

Explanation:

Given

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initial horizontal speed $u_x=14.5\ m/s$

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velocity gained by projectile during 26.7 m motion

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s=displacement

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$W_g=\Delta K$

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