Answer:
Output force = 300 N
Explanation:
Given that,
The mechanical advantage of a lever, m = 3
Input force, 
We need to find the output force. The ratio of output force to the input force is called the mechanical advantage of the lever. So,

So, the output force is 300 N.
There are no appropriate units for power on the list you provided
Answer:
Due to potential difference (elaborated in explanation)
Explanation:
When a bird sits on a power line, its whole body is in contact with the power line. It does not have any contact with the ground or anything at a lower potential. Hence, the current does not flow through the bird's body, because there is no potential difference available as a driving force.
Now, when a person touches the power line his hand is at a higher potential provided by the power line, while the rest of his body is connected to the ground, usually through legs. The current always looks for a path from high potential to low potential. Therefore, the body of the person serves as the path for the current. Heavy current flows through the body and the person dies within split seconds.
Full moon!
when Earth is exactly between the Moon and Sun, Earth's shadow falls upon the surface of the Moon, dimming it and sometimes turning the surface red over the course of a few hours.