Question

As observed in the laboratory system, a 6 MeV proton is incident on a stationary ¹²C target velocity of center of mass of the system is : (Take mass of proton to be 1 amu)

• A. 2.6 × 10⁶ m/s
• B. 6.2 × 10⁶ m/s
• C. 10 × 10⁶ m/s
• D. 10 m/s

Answer 1

Answer: (A)

2.6 × 10⁶ m/s

Answer 2

Proton velocity is found as

= K = 6 MeV

v = 3.4 × 10⁷ m/s

v_cm = $\left( \frac { m _ { i } v } { m _ { i } + M _ { i } } \right)$ = $\frac { 1 u } { 12 u + 1 u }$ (3.4 × 10⁷ m/s)

= 2.6 × 10⁶ m/s in the direction of the proton