QUESTION IMAGE
Question
part 1 questions
- describe what is happening to potential energy as the skater’s height decreases.
- describe what is happening to speed and kinetic energy as the skater’s height decreases.
- does the total energy change as the skater’s height decreases? if it does, send the skater down the track again and look at the total energy at different points. comment on any differences.
- if a quantity remains constant, we say that it is conserved. which of the following energies is conserved? potential, kinetic or total?
- how does this lab demonstrate the law of conservation of energy?
Question 1
Potential energy (specifically gravitational potential energy) is given by the formula \( PE = mgh \), where \( m \) is mass, \( g \) is acceleration due to gravity, and \( h \) is height. As the skater’s height (\( h \)) decreases, and \( m \) and \( g \) are constant (assuming no mass change and constant gravity), the potential energy will decrease.
Kinetic energy is given by \( KE=\frac{1}{2}mv^{2} \), where \( v \) is speed. As the skater’s height decreases, potential energy decreases (from Question 1). By the conservation of mechanical energy (assuming negligible friction), the lost potential energy is converted into kinetic energy. So kinetic energy increases. Since \( KE=\frac{1}{2}mv^{2} \) and mass \( m \) is constant, an increase in \( KE \) means an increase in speed \( v \) (because \( v = \sqrt{\frac{2KE}{m}} \)).
Total mechanical energy is the sum of potential energy (\( PE \)) and kinetic energy (\( KE \)), i.e., \( E_{total}=PE + KE \). In an ideal scenario with no friction (or other non - conservative forces), mechanical energy is conserved. So as the skater’s height decreases, \( PE \) decreases and \( KE \) increases, but their sum (total energy) remains constant. If there is friction, total energy would decrease slightly over time due to energy being converted into heat, but in a typical physics simulation (like the skater simulation), we assume negligible friction for the purpose of this question, so total energy does not change. If we run the skater down the track again, in the ideal case, the total energy at different points should be the same. If there is friction, the total energy might decrease a bit, but the differences would be small and due to energy dissipation.
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As the skater’s height decreases, the potential energy (gravitational potential energy) decreases. This is because gravitational potential energy is proportional to height (\( PE = mgh \)), so a lower height means less potential energy (assuming mass and gravity are constant).