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Answer:
The change in internal energy of the air within the piston is 490 J.
Explanation:
In thermodynamics the internal energy (ΔU) of a system is the total energy contained in the system and can be considered as the sum of the energy in the form of heat (q, given to or released by the system) and in the form of work (w, make by the system to the environment or from the environment to the system). When the system absorbs heat from the enviroment this value is positive, while when the system realeased heat to the enviroment, the value is negative. In the case of work, when the enviroment make work on the system, the value is positive and, on the contrary, when the system makes work against the environment the value is negative.
ΔU = q + w
w is defined as the negative product between the external pressure (P) and the change in volume (ΔV). [w = - P·ΔV]
⇒ ΔU = q - P·ΔV
In this problem, the system is composed by the cylinder + piston + contained air (Attached)
1) q= 565 J (a positive value because the enviroment delivered heat to the cylinder)
2) P = 1 atm.
3) ΔV = 0.86 atm.L - 0.12 atm.L = 0.74 atm.L.
⇒ ΔU = q + w ⇒ ΔU = 565 J - (1 atm)·(0.74 L) ⇒ ΔU = 565 J - 0.74 atm.L
We have to express the work value in the same units of heat, it means Joules. As one joule is equal to 0.00987 atm.L
⇒ (0.74 atm.L) x ( 1 J/0.00987 atm.L) = 74.97 J.
⇒ ΔU = q + w ⇒ ΔU = 565 J - 74.97 J ⇒ ΔU = 490 J.
Summarizing, the change in internal energy of the air within the piston is 490 J.
Answer:
Part a)
Velocity of sled
velocity of first man who jump off
Part b)
Velocity of sled
Also the speed of second person is given as
Part c)
change in kinetic energy of sled + two people is given as
Explanation:
As we know that here we we consider both people + sled as a system then there is no external force on it
So here we can use momentum conservation
since both people + sled is at rest initially so initial total momentum is zero
now when first people will jump with relative velocity "s" then let say the sled + other people will move off with speed v
so by momentum conservation we have
so velocity of the sled + other person is
velocity of first man who jump off
Part b)
now when other man also jump off with same relative velocity
so let say the sled is now moving with speed vf
so by momentum conservation we have
Now we have
Also the speed of second person is given as
Part c)
change in kinetic energy of sled + two people is given as
here we know all values of speed as we found it in part a) and part b)