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Zorluk: ZorGravity and Free Fall

A skydiver jumps from a stationary hot air balloon. Arrange the following moments of the jump in order of the skydiver's acceleration, starting from the greatest downward acceleration and ending with the greatest upward acceleration.

  1. 1Immediately after jumping from the stationary balloon
  2. 2Several seconds into the fall, while speed is still increasing
  3. 3Falling at a constant terminal velocity
  4. 4The exact moment the parachute fully inflates

Cevap

The correct sequence tracks the decreasing downward acceleration: immediately after jumping (maximum downward), followed by several seconds into the fall (reduced downward), then falling at terminal velocity (zero acceleration), and finally the moment the parachute inflates (strong upward acceleration).
The correct sequence tracks the net force acting on the skydiver. Initially, only gravity acts, causing maximum downward acceleration. As speed increases, upward air drag grows, reducing the net downward force and acceleration. At terminal velocity, drag equals weight, making net force and acceleration zero. When the parachute opens, drag vastly exceeds weight, creating a net upward force and thus an upward acceleration.

Adım Adım Çözüm

1
Analyze the forces acting immediately after the jump.
Velocity is zero, so air drag is zero. The only force is gravity, resulting in the maximum downward acceleration of approximately 9.8 m/s².
Air drag depends on velocity. Without velocity, there is no drag to oppose gravity.
2
Evaluate the forces during the middle of the fall before terminal velocity.
As the skydiver speeds up, upward air drag increases. The net downward force becomes less than gravity, so downward acceleration is less than 9.8 m/s².
Net force equals weight minus air drag. As drag increases, net force decreases, reducing acceleration according to Newton's Second Law.
3
Identify the conditions at terminal velocity.
Upward air drag exactly equals downward weight. The net force is zero, meaning acceleration is exactly 0 m/s².
Terminal velocity is reached when opposing forces balance out completely, ending any change in speed.
4
Assess the moment the parachute inflates.
The huge surface area creates an upward air drag much greater than the downward weight. The net force points upward, creating a strong upward acceleration.
A net upward force is required to rapidly decrease the downward velocity to a safe landing speed.

Anahtar Kavram

The relationship between gravity, air resistance, and net acceleration during free fall through an atmosphere.
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Gravity and Free Fall

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