Question

Analyze Discuss the various energy conversions that occur when a person performs a pole vault. Include as many conversions as you can. Be sure to consider times before, during, and after the vault itself.

Short answer

Chemical to kinetic to elastic to gravitational, and back to kinetic energy occur during pole vaulting.

Step-by-step solution

Initial Energy - Chemical Energy

The energy conversion process begins even before the pole vaulter starts their run. Initially, the vaulter's energy is stored in the form of chemical energy within the muscles, coming from the food intake.

Chemical to Kinetic Energy Conversion

As the vaulter begins to run down the track, the stored chemical energy in the muscles is converted into kinetic energy. This conversion enables the person to gain speed as they sprint towards the vaulting pit.

Kinetic to Elastic Potential Energy

When the vaulter plants the pole into the box, the kinetic energy of the running vaulter is transferred into the pole, causing it to bend. This bending stores energy as elastic potential energy within the pole.

Elastic Potential to Gravitational Potential Energy

As the pole straightens, it converts the stored elastic potential energy into gravitational potential energy, lifting the vaulter off the ground and upwards over the bar. This energy conversion propels the vaulter to a maximal height.

Gravitational Potential to Kinetic Energy

As the vaulter clears the bar and descends, the gravitational potential energy is converted back into kinetic energy as the vaulter falls towards the landing pad.

Kinetic Energy to Mechanical and Sound Energy

Finally, when the vaulter lands on the cushioned mat, the remaining kinetic energy is dissipated as mechanical energy, causing deformation of the mat, and some of it is also transformed into sound energy upon impact.

Key concepts

Chemical Energy

Chemical energy is the starting point in many physical activities, including sports like pole vaulting. It originates from the food we consume, which gets converted into energy forms that our body can use. Inside the body, nutrients from food are broken down, and stored energy is available in the form of chemical bonds. This chemical energy resides predominantly in molecules like ATP (adenosine triphosphate).

When a pole vaulter prepares for their run, their muscles are loaded with this chemical energy. The body initiates a series of chemical reactions that release energy, enabling muscle contraction and movement. This process transforms chemical energy into other forms necessary for athletic performance.

• Source: Chemical energy originates from digested food.
• Conversion: It's essential for initiating movement, turning into kinetic energy as the muscles contract.
• Role: Provides the initial energy for muscle function during sports activities.

Kinetic Energy

Once the chemical energy in the muscles is converted, it becomes kinetic energy. Kinetic energy is what keeps things moving and is essential when the vaulter starts running down the track. Defined as the energy of motion, kinetic energy can be calculated using the formula: \[ KE = \frac{1}{2}mv^2 \]where \(m\) represents mass and \(v\) represents velocity.

For a pole vaulter, maximizing kinetic energy is crucial because greater speed allows the conversion of kinetic energy into other forms more effectively. As the vaulter sprints towards the vaulting pit, they increase their velocity, and thus their kinetic energy.

• Source: Converted from chemical energy stored in muscles.
• Importance: Fuels the run-up, crucial for energy transfer to the pole.
• Conversion Ability: Can be transformed into potential energy during the pole plant.

Potential Energy

Potential energy is stored energy, and during a pole vault, it appears in two main forms: elastic potential energy and gravitational potential energy. As the vaulter's kinetic energy is transferred to the pole, the pole bends—storing energy as elastic potential energy.

Elastic potential energy depends on how much the pole bends, similar to stretching a rubber band. The stored energy in the bent pole is crucial because it helps in lifting the vaulter skyward. As the pole releases this energy, it converts into gravitational potential energy when the vaulter rises.

Gravitational potential energy is given by the formula:\[ PE = mgh \]where \(m\) is the mass, \(g\) is the acceleration due to gravity, and \(h\) is the height. This energy is at its peak when the vaulter is over the bar. Finally, as the vaulter descends, this stored energy changes back into kinetic energy.

• Elastic Potential: Stored in the bending pole, crucial for upward propulsion.
• Gravitational Potential: Peaked when the vaulter reaches maximum height.
• Conversion: Transfers back to kinetic energy as the vaulter descends.