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Physics Force & Laws Of Motion Level: High School

A U-238 nucleus ( mass = 238 units ) decays , transforming into an alpha particle ( mass = 4 units ) and a residual thorium nucleus ( mass = 234 units ) . If the uranium nucleus was at rest , and the alpha particle has a speed of 1.3E7 m/s . Determine the recoil speed of the thorium nucleus .