Which one of the following remains constant while throwing a ball upward?

Options

A. Displacement
B. Kinetic energy
C. Acceleration
D. Velocity

Explanation

To determine which quantity remains constant while throwing a ball upward, we can analyze the situation step by step.

### Step-by-Step Solution:

1. **Identify the Scenario**: When a ball is thrown upward, it experiences various forces and changes in motion. We need to identify which physical quantity remains constant throughout this motion.

2. **Consider the Forces Acting on the Ball**: The primary force acting on the ball is gravity, which pulls it downward. The acceleration due to gravity (denoted as \( g \)) is approximately \( 9.81 \, \text{m/s}^2 \) near the Earth's surface.

3. **Analyze the Motion**: As the ball is thrown upward, it initially has an upward velocity. However, as it rises, gravity acts against this motion, causing the ball to decelerate until it reaches its highest point (where its velocity becomes zero) and then accelerates downward.

4. **Evaluate Different Quantities**:
- **Velocity**: The velocity of the ball changes continuously as it moves upward and then downward. Therefore, velocity is not constant.
- **Kinetic Energy**: Kinetic energy depends on the velocity of the ball, which changes as the ball moves. Thus, kinetic energy is not constant.
- **Displacement**: The displacement of the ball changes as it moves upward and then downward. Therefore, displacement is not constant.
- **Acceleration**: The acceleration due to gravity (\( g \)) remains constant throughout the motion, acting downward regardless of the ball's position.

5. **Conclusion**: The only quantity that remains constant while throwing a ball upward is the acceleration due to gravity (\( g \)).

### Final Answer:
The quantity that remains constant while throwing a ball upward is the **acceleration due to gravity (g)**.

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