Given u = 28 m s⁻¹, v = 0 and s = 98 m. Using v² = u² + 2as, we get a = −4 m s⁻². Time taken, t = (v − u)/a = 7 s.
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Given, initial velocity u = 0, final velocity v = 24 m s⁻¹ and time t = 6 s. Average acceleration = (24 − 0)/6 = 4 m s⁻². Distance = ½(0 + 24) × 6 = 72 m.
Yes, the scooter can be accelerating even when its speed remains constant. This happens when its direction of motion changes, such as while moving along a circular path. Acceleration changes velocity, not necessarily speed.
(i) Average velocity equals average speed when the object moves in a straight line without changing direction. (ii) Average velocity is zero when the object returns to its starting point, although it has travelled a non-zero distance.
Total distance = 200 + 200 = 400 km and total time = 3 + 2 = 5 h. Average speed = 400/5 = 80 km/h. Since displacement is zero, average velocity = 0 km/h.