A ball is thrown vertically upwards. Which of the following graph represent velocity-time graph of the ball during its flight (air resistance is neglected)

To determine the correct graph representing the velocity-time graph of the ball during its flight, we need to consider the motion of the ball when it is thrown vertically upwards.

1. Initially, when the ball is thrown upwards, its velocity is positive and decreasing due to the gravitational force acting in the opposite direction. This means that the velocity-time graph should start with a positive slope and gradually decrease.

2. As the ball reaches its maximum height, its velocity becomes zero. This indicates that the velocity-time graph should have a point where the slope is zero.

3. After reaching the maximum height, the ball starts to fall downwards. Its velocity becomes negative and increases in magnitude due to the acceleration of gravity. Therefore, the velocity-time graph should have a negative slope that increases in magnitude.

Based on these considerations, the correct graph representing the velocity-time graph of the ball during its flight would be a graph that starts with a positive slope, reaches a point with zero slope, and then has a negative slope that increases in magnitude.