Determine the forces that are working against the object in the picture. Write an explanation or draw a free body diagram of what forces are working against the object, and explain the direction of the net force

Question

The picture is of a plane in the air

Answer 1

To analyze the forces acting on a plane in the air, we can consider a typical free-body diagram that focuses on the major forces working against the plane's motion. The primary forces in play are:

1. Weight (Gravity): This force acts downward towards the center of the Earth. It is due to the mass of the plane and the gravitational acceleration (approximately 9.81 m/s²).

2. Drag (Air Resistance): This force opposes the direction of motion of the plane through the air. As the plane moves forward, it encounters air resistance, which acts opposite to its velocity.

3. Lift: While lift is a force that acts upward, it is important to note because it counteracts the weight of the plane when in level flight. It is generated by the wings as the plane moves through the air.

4. Thrust: This is the forward force created by the plane's engines. Thrust must overcome drag for the plane to accelerate forward.

Free Body Diagram Explanation

1. Weight (Gravity): Draw an arrow pointing downwards, representing the force of gravity (weight). This force is equal to \( F_g = m \cdot g \), where \( m \) is the mass of the plane and \( g \) is the acceleration due to gravity.

2. Drag (Air Resistance): Draw an arrow pointing horizontally backward (opposite to the direction of the plane's motion), representing drag. This force can be influenced by speed, shape of the plane, and other factors.

3. Lift: Draw an arrow pointing upwards, which represents the lift force acting on the plane as it moves through the air. The magnitude of lift needs to be sufficient to counteract the weight of the plane for level flight.

4. Thrust: Draw an arrow pointing horizontally forward, representing thrust from the engines.

Net Force Explanation

Static Condition: If the plane is flying at a constant altitude and speed, the forces are balanced:

• Lift equals weight.
• Thrust equals drag.

Thus, the net force in the vertical direction is zero (Lift = Weight), meaning the plane maintains a stable altitude. Similarly, the net force in the horizontal direction is also zero (Thrust = Drag), meaning the plane is moving at a constant speed.

Dynamic Conditions: If the plane is climbing or descending, or accelerating, the net force will indicate the direction of motion:

• If Lift > Weight, the plane will ascend.
• If Weight > Lift, the plane will descend.
• If Thrust > Drag, the plane will accelerate forward.
• If Drag > Thrust, the plane will decelerate.

In summary, for a plane flying in the air, the forces working against its motion are primarily weight (gravity) and drag (air resistance), while lift and thrust work to counteract these forces. The net force determines whether the plane is climbing, descending, or maintaining a steady speed.