Question

A bus decreases its speed from \( 80 km h ^{-1} \) to \( 60 km h ^{-1} \) in \( 5 s \). Find the acceleration of the bus.

Answer 1

• Initial velocity (u) = 80 km/h = 80 × (5/18) = 22.2 m/s
• Final velocity (v) = 60 km/h = 60  × (5/18) = 16.7 m/s
• Time (t) = 5 s
• Formula

v = u + at is the first equation of motion.

where,

u is initial velocity

v is the final velocity

a is acceleration

t is the time period

v = u + at

a = v – u/t

a = 16.7 – (22.2/5)

a = -1.1 m/s2