Question

<Hw 15 (Ch 43) FLC Phys 431 Fall 2019 Problem 43.52 41 of 69 41 of 69 > Constants Thorium 20 Th decays to radium Ra by a emission. The masses of the neutral atoms are 230.033134 u for 330 Th and 226.025410 u for 226 Ra. Part A If the parent thorium nucleus is at rest, what is the kinetic energy of the emitted a particle? (Be sure to account for the recoil of the daughter nucleus.) Express your answer using three significant figures. IVO ALQ ? R o 2 - K = MeV Mev Submit Request Answer

Answer 1

Ans:

Given data

Mass of parent atom is M_P=230.033134 u

Mass of daughter is M_D= 226.025410 u

Mass of alpha particle m = 4.0026 u

Find the Q value of alpha particle by using formula below

Q= (M_P – M_D – m) c²

   = (230.033134 u -226.025410 u- 4.0026 u) c²

   = 5.124*10^-3 u c²

1u= 931.5 Mev/ c²

Q= (5.124*10^-3 u c²)*( 931.5 Mev/ c²)

   =4.773 Mev

Use kinetic energy formula

T= ( A/(A+4))Q

  =( 226/(226+4)) 4.773 Mev

= 4.690 Mev