When a bus moves suddenly, the person standing in it tilts backwards. This concept is explained using inertia (tendency of body to resist change in its state of motion) but when the bus moves suddenly, can't we also say that the torque applied due to friction force on our feet causes our upper body to move backwards?
It should also be noted that the person tilting backward on the bus is not experiencing a real force but a pseudo force on the upper body, that is, a force that appears to be acting on the person because the persons motion is described in a non-inertial reference frame.
can't we also say that the torque applied due to friction force on our feet causes our upper body to move backwards?
The static friction force prevents the bottom part of the body from moving backwards as opposed to causing the upper part of the body to move backwards.
Hope this helps.