Final answer:
A bicyclist may have less kinetic energy from point A to B due to energy transformations, such as the conversion of mechanical energy into heat through friction and air resistance. Tire temperature rising indicates kinetic energy being lost as heat. Furthermore, in cycles of motion like pedaling or when dealing with collisions, kinetic energy can be reduced due to various energy conversions, leading to less motion or speed.
Step-by-step explanation:
The reason why a bicyclist has less kinetic energy when moving from point A to point B can involve several factors depending on the specific scenario proposed. One possibility is that part of the mechanical energy, which includes kinetic and potential energy, might be converted into heat through friction.
When a cyclist coasts down a hill and up another one, some of the original potential energy (denoted by the height of the hill) is transformed into kinetic energy as they descend. However, as they climb up the other hill, that kinetic energy is subsequently converted back into potential energy until they reach a point where they stop.
Since they stop at a point lower than the start, it implies that not all the potential energy has been reconverted into kinetic energy. This is often because some of the energy is transformed into other forms, such as heat due to friction between the bicycle tires and the road.
Rise in tire temperature is a common indication of this energy transformation. Additionally, air resistance can also play a role in reducing the bicyclist's kinetic energy, as energy is spent to overcome the force of the air pushing against the motion.
In the case of a collision where internal kinetic energy is calculated before and after, a reduction after the collision signals an inelastic collision, indicating that some of the system's kinetic energy has been converted to other forms of energy, such as sound or deformation of the involved objects. Similarly, during swinging or rotating motions, energy is divided between translational kinetic energy and rotational kinetic energy, which affects how fast an object can translate or move through space.
For inertia, it is a measure dependent solely on mass when there's no velocity involved. Since a 2,000-kg car has a significantly greater mass than a 60-kg bike and rider, option 'a' is correct: The car has more inertia due to its greater mass.