by the concept of momentum conservation we can say
if net force on a system of mass is ZERO then its momentum will remain conserved
Here a ball is projected upwards so if we take Ball + Earth as a system then total momentum of the system will remain conserved
Initially when ball is on the surface of earth the system has zero momentum and hence we can say after throwing the ball momentum of earth + ball must be zero
now using same equation we can say
given that
from above equation velocity of earth will be
so above will be the recoil speed of earth
The electric field E of a charge is defined as E=F/Q where F is the Coulomb force and Q is the test charge.
E=(1/Q)*k*(q*Q)/r², where k=9*10^9 N*m²/C², q is the point charge, Q is the test charge and r is the distance between the charges.
So E=(k*q)/r²
When we input the numbers we get that electric field E of a point chage q is:
E=(9*10^9)*(5.4*10^-8)/0.2²=486/0.04=12150 N/C.
This is roughly E=12000 N/C =1.2*10^4 N/C
The correct answer is B.
I think it's C, longer wave length.
A is correct according to below calculation.
m₁v₀₁+m₂v₀₂=m₁v₁+m₂v₂
((m₁v₀₁+m₂v₀₂)-m₁v₁)/m₂=v₂
v₂=((.5*12-.75*16)+(.5*21.6))/.75
v₂=6.4 m/s
