Two cyclists, X and Y, begin at the same position and ride along a straight path for 4 s. Their motion is described below.
• Cyclist X travels at a constant speed of 10 m/s for the first 2 s and then comes to rest, remaining stationary for the next 2 s.
• Cyclist Y covers 2 m during the first 2 s. After that, her speed increases smoothly so that she has traveled a total of 22 m by t = 4 s. The slope of her position–time curve at t = 4 s is twice its slope at t = 3 s.
At t = 3 s, which cyclist has the greater instantaneous velocity, and which has the greater instantaneous acceleration?
(a) Velocity: X Acceleration: Y
(b) Velocity: X Acceleration: X
(c) Velocity: Y Acceleration: Y
(d) Velocity: Y Acceleration: X