A uranium 238 nucleus, initially at rest emits n alpha particle with a speed of `1.4xx10^7m/s`. Calculte the rcoil speed of the residual nucleus thorium 234. Assume that the mas of a nucleus is proprotional to the mass number.

Explanation

To solve the problem of finding the recoil speed of the residual nucleus (thorium-234) after the emission of an alpha particle from a uranium-238 nucleus, we can use the principle of conservation of momentum. Here’s a step-by-step solution:

### Step 1: Understand the Problem
We have a uranium-238 nucleus that is initially at rest. It emits an alpha particle, and we need to find the recoil speed of the thorium-234 nucleus that remains after the emission.

### Step 2: Identify the Masses
- The mass number of uranium-238 is 238.
- The mass number of the emitted alpha particle is 4 (since an alpha particle consists of 2 protons and 2 neutrons).
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