- #1

bdolle

- 10

- 1

1. When W>0 the system's energy increases, when W<0 the system's energy decreases.

2.

**ΔE**=

**ΔK+**

**ΔU+****ΔTherm = W**3.

**ΔU = -W**

Here is where my confusion begins. If I move a 1kg brick from 0m to 1m I have added potential energy, more energy is stored in the system. Statement 2 asserts that because

**ΔU**increases,

**ΔE**will also increase and work will be positive. Statement 1 says that W>0 so the system's energy increases. But statement 3 says that

**ΔU= -W**, but we can see clearly that

**ΔU**was positive and that work is also positive.

I am missing something. Please help.