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1. An atomic nucleus initially moving at 408m/s emits an alpha particle in the d

ID: 1438256 • Letter: 1

Question

1. An atomic nucleus initially moving at 408m/s emits an alpha particle in the direction of its velocity, and the new nucleus slows to 340m/s. If the alpha particle has a mass of 2u and the original nucleus has a mass of 222u, what speed does the alpha particle have when it is emitted?

2.A 1.20kg box slides down a rough incline plane from a height h of 1.87m. The box had a speed of 2.11m/s at the top and a speed of 1.68m/s at the bottom. Calculate the mechanical energy lost due to friction (as heat, etc.).

Explanation / Answer

By energy conservation

Pi = Pf

(m1 + m2)*U = m1v1+m2v2

v2 = ((m1+m2)U - m1v1)/m2

v2 = ((222*408 - 220*340)/2 = 7888 m/sec