Explanation:
Given that,
The mean kinetic energy of the emitted electron, 
(a) The relation between the kinetic energy and the De Broglie wavelength is given by :



(b) According to Bragg's law,

n = 1
For nickel, 



As the angle made is very small, so such an electron is not useful in a Davisson-Germer type scattering experiment.
Forces are exerted I believe : all of the above
The action force might be Tyler throwing the ball
I don't know the last one
PART a)
Before Drew throw Lily in forwards direction they both stays at rest
So initial speed of both of them is zero
So here we can say that initial momentum of both of them is zero
So total momentum of the system initially = ZERO
PART b)
Since there is no external force on the system of two
so there will be no change in the momentum of this system and it will remain same as initial momentum
So final momentum of both of them will be ZERO
PART c)
As we know that momentum of both will be zero always
so we have


in opposite direction
Answer:
v ≈ 7900 m/s
Explanation:
centripetal force will equal gravity force
mv²/R = mg
v²/R = g
v² = Rg
v = √(Rg)
v = √(6.4e6(9.8))
v = 7.91959...e+3
v ≈ 7900 m/s
of course, at those velocities and that deep into the atmosphere, the satellite would quickly burn up, slow down, and cause tremendous damage to buildings etc. with the sonic boom shock wave. It would also have to avoid a lot of mountains as 4000 m is not that high.
The substance is DNA and it would be found in the nucleus.