Answer:

Explanation:
According to the law of conservation of linear momentum, the total momentum of both pucks won't be changed regardless of their interaction if no external forces are acting on the system.
Being
and
the masses of pucks a and b respectively, the initial momentum of the system is

Since b is initially at rest

After the collision and being
and
the respective velocities, the total momentum is

Both momentums are equal, thus
Solving for 


The initial kinetic energy can be found as (provided puck b is at rest)


The final kinetic energy is


The change of kinetic energy is

<em>"A concave lens is thinner at the center than it is at the edges."</em>
If this isn't on the list of choices, that's tough. We can't help you choose the best one if we don't know what any of them is.
Answer:
t = 120.5 nm
Explanation:
given,
refractive index of the oil = 1.4
wavelength of the red light = 675 nm
minimum thickness of film = ?
formula used for the constructive interference

where n is the refractive index of oil
t is thickness of film
for minimum thickness
m = 0


t = 120.5 nm
hence, the thickness of the oil is t = 120.5 nm