Answer:
Explanation:
We will use the KE equation you wrote here and fill in what we are given:
and isolating the m:
which gives us
m = .50 kg
Answer:

Explanation:
Given that,
Frequency of a radio antenna is 1 MHz
Power, P = 21 kW
We need to find the the waves intensity 25 km from the antenna
. The object emits intenisty evenly in all direction. It can be given by :

So, the wave intensity 25 km from the antenna is
.