Page 50 - text book form physics kssm 2020
P. 50

Solution:


                    Velocity, v / m s –1                                   Table 2.5

                   20                                     Time        Displacement      Acceleration
                   18
                   16                                    0 s – 10 s  Displacement     Acceleration
                                                                   = area A           = gradient of
                   14
                   12                                              = 10 × 10           the graph
                                                                                            –2
                                                                   = 100 m            = 0 m s
                   10
                    8                                    10 s – 30 s  Displacement    Acceleration
                    6  A        B        C                         = area B           =   16 – 10
                                                                      1
                    4                                              =       (10 + 16)(20)   30 – 10 –2
                                                                      2
                    2                                              = 260 m            = 0.3 m s
                    0                              Time,
                       5 10152025 3035 40 45 50    t / s  30 s – 50 s  Displacement   Acceleration
                                                                   = area C              0 – 16
                                Figure 2.32                                           =
                                                                      1                 50 – 30
                                                                   =       × 20 × 16          –2
                   Displacement after 30 s  = 100 + 260               2               = –0.8 m s
                                         = 360 m                   = 160 m
                   Displacement after 50 s  = 100 + 260 + 160
                                         = 520 m


                   (a)    Displacement-time graph            (b)    Acceleration-time graph
                                                               Acceleration, a / m s –2
                     Displacement, s / m
                                                              0.3
                                                              0.2
                   520
                   500                                        0.1
                                                               0                               Time, t / s
                   400                                       –0.1    10    20   30   40    50
                   360                                       –0.2
                   300                                       –0.3
                                                             –0.4
                   200                                       –0.5
                                                             –0.6
                   100                                       –0.7
                                                             –0.8
                     0                              Time, t / s  –0.9
                           10   20   30    40   50


                                                                           Figure 2.34
                                Figure 2.33





                  44
                  44                                                                               2.2.5
                                                                                                   2.2.5
   45   46   47   48   49   50   51   52   53   54   55