RI 1998 Sec 3 EOY P2 Q1
The head of a snake may be considered to have a uniform acceleration of 50 m/s² when striking a victim.
(a) Explain what is meant by the phrase uniform acceleration.
(b) On the axes below, show how the speed of the snake's head varies with time as it accelerates uniformly from rest.
(c) The snake strikes its victim after a time interval of 0.15 s.
Use your speed-time graph in (b) to determine
(i) the speed of the snake's head just befoer striking its victim,
(ii) the distance moved by the snake's head.
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Answer:
(a) Uniform accelerations refers to a constant increase of velocity per second in the same direction.
(b)
(c)
(i) From the graph,
gradient = (50 - 0) / (1 - 0) = 50
Thus, (v - 0) / (0.15 - 0) = 50
v = 0.15 * 50 = 7.5 m/s
(ii) Distance moved by the snake's haed = area under graph
= ½ * 7.5 * 0.15
≈ 0.56 m
