The bus speed is 10 m s⁻¹. During reaction, it travels 5 m. Braking distance = 10²/(2 × 2.5) = 20 m. Total stopping distance = 25 m, less than 30 m. Yes, it stops safely.
A bus is travelling at 36 km h⁻¹ when the driver sees an obstacle 30 m ahead. The driver takes 0.5 seconds to react before pressing the brake. Once the brake is applied, the velocity of the bus reduces with constant acceleration of 2.5 m s⁻². Will the bus be able to stop before reaching the obstacle?
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The initial speed is 36 km h⁻¹ = 10 m s⁻¹. During the reaction time of 0.5 s, distance travelled = 10 × 0.5 = 5 m. Braking distance is given by v² = u² + 2as: 0 = 100 − 5s, so s = 20 m. Therefore, total stopping distance = 5 + 20 = 25 m. Since the obstacle is 30 m away, the bus stops 5 m before it.
For more NCERT Solutions of Class 9 Science Exploration Chapter 4 Describing Motion Around Us Question Answer (2026-27)
https://www.tiwariacademy.com/ncert-solutions/class-9/science/exploration-chapter-4/