An observer is standing inside a lift moving upwards with an acceleration a. A mass m is lying on the floor of the lift. Find the normal reaction between the block and the floor.

Explanation

To solve the problem of finding the normal reaction between the block and the floor of the lift, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Forces Acting on the Mass:**
- The mass \( m \) experiences two primary forces:
- The gravitational force acting downwards, which is \( mg \) (where \( g \) is the acceleration due to gravity).
- The normal force \( N \) acting upwards from the floor of the lift.
...