Physics
Physics
Problem
A cyclist starts from rest at point A on a straight, level road. He first pedals with uniform acceleration for a certain time and then continues to ride with the constant speed he has reached. (i) Explain the difference between uniform acceleration and uniform velocity, using the cyclist’s motion to illustrate each term. (ii) The cyclist accelerates for 10 s and then rides at the constant speed for the next 50 s. List the physical quantities that must be known (or measured) in each time interval to calculate the displacement during that interval, and give a brief reason for each choice. (iii) If the total displacement from A after the 60 s of motion is 400 m, describe in words a two-stage calculation that would allow you to obtain this result. Indicate clearly which time interval each stage refers to and what unknown would be calculated in each stage.Intuitive explanation
The key to this problem is recognizing that motion has two distinct phases: one where velocity is changing (acceleration) and one where it's constant. Understanding what information you need in each phase—and why—reveals how displacement depends on different combinations of initial conditions, rates of change, and time. The second part asks you to work backward from total distance to find a missing piece, using the constraint that both phases must add up to 400 m.
Intuitive explanation
The key to this problem is recognizing that motion has two distinct phases: one where velocity is changing (acceleration) and one where it's constant. Understanding what information you need in each phase—and why—reveals how displacement depends on different combinations of initial conditions, rates of change, and time. The second part asks you to work backward from total distance to find a missing piece, using the constraint that both phases must add up to 400 m.