a falling diver straighten her legs to increase her legs to increase her surface area this cause the sky driver. explain why her legs causes to accelerate upwards

The question seems to be asking why a skydiver would accelerate upwards when she straightens her legs to increase her surface area. However, this is a misunderstanding. The skydiver does not accelerate upwards. Instead, by increasing her surface area, she slows her descent. Here's why:

1. When the skydiver jumps from the plane, gravity pulls her towards the ground, causing her to accelerate downwards. This is known as free fall.

2. As she falls, she encounters air resistance, which acts in the opposite direction to her motion. At first, the force of gravity is much stronger than the air resistance, so she continues to accelerate downwards.

3. If the skydiver tucks her body in, she presents a smaller surface area to the oncoming air, which reduces the air resistance. This allows her to fall faster.

4. If she straightens her body and spreads her arms and legs, she presents a larger surface area to the oncoming air. This increases the air resistance.

5. The increased air resistance slows her descent. If she increases her surface area enough, the air resistance can become as strong as the force of gravity. When this happens, she stops accelerating and falls at a constant speed. This is known as terminal velocity.

6. It might appear as if the skydiver is moving upwards when she increases her surface area because her descent slows down. However, she is still moving downwards, just at a slower speed.