here is the post. One type of motion I often think about happens when I ride my bicycle on hilly back roads near my home. As I pedal up a hill, my velocity decreases even though I'm applying force, because gravity is working against me. Then, when I coast downhill without pedaling, my velocity increases quickly as gravity accelerates the bike downward. The velocity is clearly not constant, and the acceleration changes depending on whether I'm going uphill or downhill. If I wanted to describe this to someone who couldn't see it, I would say the bike starts with forward motion that slows as the slope rises, then transitions to faster and faster forward motion when the slope descends. A diagram showing the slope of the road and arrows for velocity and acceleration would definitely help illustrate these changes. Thinking about this in scientific terms makes me wonder how precisely I could measure my speed and acceleration on different slopes. A speedometer might give me accurate values for velocity at a given moment, but measuring acceleration would require comparing velocity over time, and my own timing with a stopwatch might not be very precise. Describing motion using accuracy and precision helps me realize the importance of choosing the right measurement tools in understanding motion. Even in a simple bike ride, velocity and acceleration are constantly changing in measurable ways