Answer:
(a)
(b) 
Explanation:
Part (a)
The total length of copper cord L=86.3 m
The cross sectional area A=1.71×10⁻⁶m²
The resistivity of copper p=1.72×10⁻⁸Ω
Thus the resistance of extension cord is

Part (b)
The resistance of trimmer Rt=17.9 ohms
When voltage of 120V is applied then the current I is passing through series circuit is

Thus the voltage across the trimmer is:

Theoritically
the body moving with uniform velocity has acceleration zero.
Mathmatically,
u=3m/s
v=3m/s (since body is moving with uniform velocity)
a= v-u/t
3-3/t
0/t
0m/s.s
It might be radiation and reflection but I’m not sure
Your answer would be A):Organize a laboratory in Germany.
You are correct...amplitude will be the answer