Advanced Knowledge of Distance/Displacement - Time Graph
Distance in nth second(distance-time graph)
Distance traveled in nth second can be found using distance time-graph. In the given figure, distance after 21s is d2=21m and after 20s is d1=20m. Hence, distance traveled in 21st sec is d2−d1=1m.
Average velocity from a displacement-time graph
Average velocity equals the ratio of net displacement and the time taken. Example: In the given plot, for t∈(0,10), Displacement s=−4−0=−4 Hence, average velocity is given by v=s/t=−4/10=−0.4m/s
Calculation of net force from given velocity time graph
A block of mass 12 kg is hanging with a light string in a lift as shown in the figure (a). The lift is moving in upward direction and its speed time graph is plotted as shown in the figure (b) : (take g=10m/s2): In the time interval t=0 to t=5, the acceleration a=5−010−0=2m/s2 Hence T=m(g+a) T=12×(10+2)=144N In the time interval t=5 to t=10, the acceleration a=0 Hence T=mg=12×10=120N In the time interval t=10 to t=15, the acceleration a=15−1030−10=4m/s2 Hence T=m(g+a) T=12×(10+4)=168N