A ball is thrown vertically upwards. It goes to a height 20 m and then returns to the ground. Taking acceleration due to gravity g to be `10 "m s"^(-2)` ?, find the initial velocity of the ball

Explanation

To find the initial velocity of a ball thrown vertically upwards that reaches a height of 20 m before returning to the ground, we can use the third equation of motion. Here’s a step-by-step solution:

### Step 1: Identify the known values
- Maximum height (h) = 20 m
- Acceleration due to gravity (g) = 10 m/s² (acting downwards)
- Final velocity (v) at the maximum height = 0 m/s (the ball stops momentarily at the highest point)

### Step 2: Write the third equation of motion
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