Which of the following is not a projectile ?

Options

A. An aircraft taking off
B. A bullet fired from a rifle
C. A ball thrown horizontally from a roof
D. A football kicked by a player

Answer

To determine which of the following options is not a projectile, we need to analyze each option based on the definition of projectile motion. A projectile is an object that is thrown into the air with an initial velocity and moves under the influence of gravity alone, meaning that the only force acting on it after it is projected is gravity.

### Step-by-Step Solution:

1. **Understand the Definition of a Projectile**:
- A projectile is an object that is launched into the air and is only influenced by the force of gravity after its launch. This means that no other forces (like thrust or lift) should be acting on it.

2. **Analyze Each Option**:
- **Option 1: An aircraft taking off**:
- An aircraft during takeoff is powered by engines, which provide thrust. This means that there are forces acting on the aircraft other than gravity (specifically, thrust from the engines). Therefore, it does not qualify as a projectile.
- **Option 2: A bullet fired from a rifle**:
- Once the bullet leaves the barrel, it is influenced primarily by gravity and air resistance. It moves in a parabolic trajectory, making it a projectile.
- **Option 3: A ball thrown horizontally from a roof**:
- Similar to the bullet, once the ball is thrown, it is influenced by gravity and follows a parabolic path. Thus, it is also a projectile.
- **Option 4: A football kicked by a player**:
- After being kicked, the football moves under the influence of gravity and air resistance, following a parabolic trajectory. Hence, it is a projectile as well.

3. **Conclusion**:
- Based on the analysis, the only option that does not fit the definition of a projectile is **Option 1: An aircraft taking off**. This is because it is influenced by additional forces (thrust from engines) besides gravity.

### Final Answer:
**Option 1: An aircraft taking off is not a projectile.**

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