An empty freight elevator is equipped with an electronic sensor that records its…
PHYSICS · Multi-part · CBSE · Physics · Force and Laws of Motion · Force and Laws of Motion
Problem
An empty freight elevator is equipped with an electronic sensor that records its vertical acceleration as a function of time. A technician of mass 80kg carrying a 15kg toolbox enters the elevator and stands on a floor scale at t=0s. The sensor later prints the following verbal report of the elevator’s vertical acceleration a(t):
• 0≤t<2s : a=+3.0m/s2 (upward)
• 2≤t<6s : a=0
• 6≤t<8s : a=−4.5m/s2 (downward)
• 8≤t<9s : a=0
• 9≤t<11s : a=+1.0m/s2 (upward)
Assume g=9.8m/s2.
(a) For the interval 0≤t<11s, construct a labeled sketch of what the scale reading versus time graph would look like. Indicate relative magnitudes clearly but do not compute exact numerical values on the sketch.
(b) Calculate the maximum value registered by the scale during the entire 11-second ride. Identify the time interval in which this maximum occurs.
(c) Determine the minimum value registered by the scale and state the interval during which it occurs.
(d) At t=11s the technician steps off the scale but remains inside the elevator. Predict qualitatively how the elevator’s motion would be affected, if at all, by the removal of the technician’s weight. Justify your answer.