An engineer claims to have made a very fast toy truck. 

Do you think the acceleration is constant (make a sketch of a velocity-time graph of the toy's velocity (in m/s) as a function of time)? What is the average acceleration of the toy at (i) 0 and 1.5 s; (ii) 1.5 and 12 s (iii) 12 and 25 s?

• A. Acceleration is not constant; a_av-i = 10 m/s²
  a_av-ii = 5.98 m/s²
  a_av-iii = 0.477 m/s²
• B. Acceleration is not constant; a_av-i = 10 m/s²
  a_av-ii = 14.5 m/s²
  a_av-iii = 0.752 m/s²
• C. Acceleration is constant; a_av-i = 10 m/s²
  a_av-ii = 10 m/s²
  a_av-iii = 10 m/s²
• D. Acceleration is constant; a_av-i = 7.52 m/s²
  a_av-ii = 7.52 m/s²
  a_av-iii = 7.52 m/s²

Answer: (A)