A bus starting from a bus-stand and moving with uniform acceleration attains a speed of 20 km/h in 10 minutes. What is its acceleration ?

To find the acceleration of the bus, we use the kinematic formula for uniform acceleration: a = (v - u) / t, where 'v' is the final velocity, 'u' is the initial velocity, and 't' is the time. The bus starts from a bus-stand, implying an initial velocity (u) of 0 km/h [1]. The final velocity (v) is given as 20 km/h. The time (t) is 10 minutes, which must be converted to hours to match the required unit of km/h². Since 60 minutes equals 1 hour, 10 minutes is 10/60 or 1/6 hour [1]. Substituting these values into the formula: a = (20 km/h - 0 km/h) / (1/6 h). This simplifies to a = 20 * 6, resulting in an acceleration of 120 km/h².

Sources

1. [1] Science-Class VII . NCERT(Revised ed 2025) > Chapter 8: Measurement of Time and Motion > Speed = Total distance covered Total time taken > p. 113