Question

science, unit 1 - energy
name:
monday
date
lifework
a parachute falls very slowly down to the ground.

1. diagram the energy as the parachute falls to the ground.
2. how can you explain why the parachute falls so slowly to the ground? (hint: think about where the kinetic energy is going.)

Explanation:

Step1: Identify energy types

At the start, the parachute has gravitational - potential energy ($PE = mgh$) due to its height $h$ above the ground, mass $m$, and gravitational acceleration $g$. As it falls, this potential energy is converted into kinetic energy ($KE=\frac{1}{2}mv^{2}$) and thermal energy due to air - resistance.

Step2: Diagram energy conversion

Draw a height - energy graph. At the top, mark a large bar for gravitational potential energy. As the parachute falls, the gravitational potential energy bar decreases while the kinetic energy bar increases slightly and the thermal energy bar (due to air - resistance) increases. At the ground, gravitational potential energy is zero, kinetic energy is a small non - zero value, and thermal energy is the largest value.

Step3: Explain slow fall

The parachute has a large surface area. As it falls, air molecules collide with the parachute. The kinetic energy of the falling parachute is transferred to the air molecules through these collisions. This air - resistance force opposes the motion of the parachute, converting a large amount of the kinetic energy that would otherwise make it fall fast into thermal energy of the air molecules, thus making it fall slowly.

Answer:

1. See the above description for how to diagram the energy conversion.
2. The large surface area of the parachute causes significant air - resistance. The kinetic energy of the parachute is transferred to the air molecules through collisions, converting it into thermal energy and reducing the speed of the fall.