To find the height to which the lift takes the passenger, we need to calculate the displacement. The displacement is given by the area under the speed-time (v-t) graph .
Based on the standard graph associated with this specific problem (often found in competitive exams like NEET/AIPMT 2013), the motion corresponds to a trapezium with the following phases:
- Acceleration: From t=0 to t=2 s, speed increases from 0 to 3.6 m/s.
- Constant Speed: From t=2 to t=10 s, speed remains constant at 3.6 m/s.
- Deceleration: From t=10 to t=12 s, speed decreases from 3.6 m/s to 0.
Calculation:
Height=Area under the curve=Area of Trapezium
Area=21×(Sum of parallel sides)×(Height)
Sum of parallel sides = Total time + Time of constant motion = 12 s+(10−2) s=12+8=20 s. Height of graph = Maximum speed = 3.6 m/s.
Height=21×(20)×3.6
Height=10×3.6=36 meters
The mass of the lift (1500 kg) is not required for calculating the displacement from the v-t graph.