Step-by-step explanation:
Given that,
Mass of bus, m = 6110 kg
Speed of bus, v = 20 m/s
The bus will stop in 24 s gently applying the brakes, t = 24 s
The average force exerted on the bus is given by :
![Ft=mv\\\\F=(mv)/(t)\\\\F=(6110* 20)/(24)=5091.67\ N](https://img.qammunity.org/2021/formulas/physics/high-school/frrlibjifmd8zeurcsvi8u2w32bgto3wwn.png)
If the driver slams on the brakes, the stops in 3.90 s, t' = 3.9 s
The average force exerted on the bus at this time is given by :
![F't=mv\\\\F'=(mv)/(t')\\\\F'=(6110* 20)/(3.9)=31333.34\ N](https://img.qammunity.org/2021/formulas/physics/high-school/8ad9ib2zhtjffqnv1xhrtvjv3b78mqc7zu.png)
Hence, this is the required solution.