Question

What is the value of impact parameter for a head on collision?

Answer 1

The impact parameter {\displaystyle b} is defined as the perpendicular distance between the path of a projectile and the center of a potential field {\displaystyle U(r)}created by an object that the projectile is approaching (see diagram). It is often referred to in nuclear physics (see Rutherford scattering) and in classical mechanics.

The impact parameter is related to the scatteringangle {\displaystyle \theta } by[1]

{\displaystyle \theta =\pi -2b\int _{r_{\mathrm {min} }}^{\infty }{\frac {dr}{r^{2}{\sqrt {1-(b/r)^{2}-2U/mv_{\infty }^{2}}}}}}

where {\displaystyle v_{\infty }} is the velocity of the projectile when it is far from the center, and {\displaystyle r_{\mathrm {min} }} is its closest distance from the center

Answer 2

• The value of impact parameter for a head on head collision is zero.
• The impact parameter is the perpendicular distance between the path of a projectile and the center of a potential field.
• The point where the alpha particle would reverse its direction  the scattering angle would be equal to 180.
• If the line of incident of the alpha particles is at distance b, from the nucleus.
• And b is called impact parameter.
• Impact parameter id=s directly proportional to cot of half of the angle.
• For a head on collision  the angle is 180 degrees thus the half of the angle is 90 degrees.
• And cot 90 degrees is equal to zero.
• Thus the impact parameter is zero.