Question

while cruising along dark stretch of highway at a speed of 25 m/s you see that bridge ahead has been washed out. you apply the breaks to and come to a stop in 4.0 sec

construct the position vs time graph and acceleration vs time graph and motion graph for 4 sec interval

Answer 1

55 mph

Answer 2

  Velocity
  (m ⁄ sec)
       ↑
  25     | \
   |  \
   |  \
   |   \
   |   \
   |    \  slope = acceleration
   |     \
   |       \
——   0   |—ı—ı—ı—ı———→ Time (seconds)
       0         4


  a = (ΔV) ∕ (Δt) ... (change in velocity) ∕ (change in time)
  a = (0 – 25) ∕ (4 – 0)
  a = - 6.25 m/sec² ... acceleration is negative because it it slowing down