First, use a high-quality measurement tool. Next, measure carefully. Finally, repeat the measurement a few times. Hope it helps!
I belive it could be 6.5 but I could be wrong
Answer:
B. QC > 0; QH < 0
Explanation:
Given that there are two reservoir of energy.
Sign convention for heat and work :
1.If the heat is adding to the system then it is taken as positive and if heat is going out from the system then it is taken as negative.
2. If the work is done on the system then it is taken as negative and if the work is done by the system then it is taken as positive.
From hot reservoir heat is going out that is why it is taken as negative

From cold reservoir heat is coming inside the reservoir that is why it is taken as positive

That is why the answer will be
,
I would say that this is the first law of thermodynamics.
Answer:
V = 6.3 m/s
Explanation:
Given:
m₁ = 2 kg
m₂ = 18 kg
m₃ = 9 kg
V₁ = 10 m/s
V₂ = 8 m/s
V₃ = 2 m/s
__________
V - ?
Let us write the momentum conservation law for an inelastic impact:
m₁·V₁ + m₂·V₂ + m₃·V₃ = (m₁ +m₂ + m₃) ·V
Cart speed after interaction:
V = ( m₁·V₁ + m₂·V₂ + m₃·V₃ ) / (m₁ +m₂ + m₃)
V = (2·10 + 18·8 + 9·2) / ( 2 + 18 + 9) = 182 / 29 ≈ 6.3 m/s