Answer:

Explanation:
The index of refraction is equal to the speed of light c in vacuum divided by its speed v in a substance, or
. For our case we want to use
, which for our values is equal to:

Which we will express with 3 significant figures (since a product or quotient must contain the same number of significant figures as the measurement with the <em>least</em> number of significant figures):

Answer:
The pushing force and the skier's mass
(A) is correct option.
Explanation:
Given that,
Mass = 64 kg
Weight = 608 N
Velocity = 21 m/s
Forward force = 45 N
We need to calculate the reaction force of the snow pushing on the skier
Using given data,
The reaction force of the snow pushing on the skier is equal to the pushing force and the skier's mass.
Hence, The pushing force and the skier's mass
(A) is correct option.
Answer:

Explanation:
The magnetic field strength is given by:

where
is the vacuum permeability
I is the current
r is the distance from the wire
In this problem,
I = 6.5 A
r = 6.3 cm = 0.063 m
So, the magnetic field strength is

Answer is C. Because protons and neutrons are more massive then electrons so that means A and b and C are not right