Which of the following is a way to improve the efficiency of a heat engine?
increase Qh
reduce Qh
reduce Wnet
increase Qc
A
What are the energies associated with atomic motion called?
kinetic energy
potential energy
bond energy
internal energy
D
A 0.10 kg piece of copper at an initial temperature of 95°C is dropped into 0.20 kg of water contained in a 0.28 kg aluminum calorimeter. The water and calorimeter are initially at 15°C. What is the final temperature of the system when it reaches equilibrium?
mw = 0.20kg
cp,w = 4186J/kg°C
mAl = 0.28kg
cp,Al = 899J/kg°C
Tw = TAl = 15°C
mCu = 0.10kg
cp,Cu = 387J/kg°C
TCu = 95°C
18
Thank you!
To improve the efficiency of a heat engine, you can make any of the following changes:
1. Increase Qh (heat input): By providing more heat to the engine, you can increase the temperature difference between the hot and cold reservoirs, allowing for more efficient energy conversion.
2. Reduce Qc (heat output): By reducing the amount of heat transferred to the cold reservoir, you can minimize energy loss and improve efficiency.
3. Reduce Wnet (net work output): By reducing the amount of work done by the engine, you can reduce energy losses and improve efficiency.
Among the given options, increasing Qh is the most effective way to improve the efficiency of a heat engine. So, in this case, the correct answer is "increase Qh."
Regarding the second question, the energies associated with atomic motion are known as internal energy. Internal energy includes both the kinetic energy (energy of motion) and potential energy (energy due to position) of the atoms or molecules within a substance. So, the correct answer is "internal energy."
Lastly, to find the final temperature of the system when it reaches equilibrium, you need to use the principle of energy conservation. The heat gained by the water and calorimeter (Qw) plus the heat gained by the aluminum (QAl) should equal the heat lost by the copper (QCu).
The equation for energy conservation in this case is:
(mw * cp,w * (Tf - Tw)) + (mAl * cp,Al * (Tf - TAl)) = mCu * cp,Cu * (Tf - TCu)
By substituting the given values into the equation and solving for Tf, you can find the final temperature of the system when it reaches equilibrium. In this case, the answer is 18°C.