A force `2bar(i)+bar(j)-bar(k)` Newton acts on a body which is initially at rest . At the end of 20 seconds the velocity of the body is `4bar(i)+2bar(j)-2bar(k)` m/s . What is the mass of the body ?

Explanation

To find the mass of the body given the force acting on it, we can use Newton's second law of motion, which states that the force acting on an object is equal to the mass of the object multiplied by its acceleration (F = m * a).

### Step-by-step Solution:

1. **Identify the Given Values:**
- Force \( \vec{F} = 2\hat{i} + \hat{j} - \hat{k} \) Newton
- Initial velocity \( \vec{u} = 0 \) (body is initially at rest)
- Final velocity \( \vec{v} = 4\hat{i} + 2\hat{j} - 2\hat{k} \) m/s
...