The force and acceleration *during* a collision depend on how long the collision lasts (the contact time, t, between initial contact and the objects reaching their final velocities).
Two hard objects (e.g. steel) bouncing off each other might only have a short contact time of, say, t = 0.01s. Two softer colliding objects (e.g. rubber) will have a longer contact time, e.g. t= 0.1s.
As an example: during a collision object A (m=5kg) changes its velocity from 2m/s to -1m/s; the contact time with the other object is t=0.02s, then:
A’s velocity change Δv = (-1) – 2 = -3m/s.
A’s acceleration = Δv/t = -3/0.02 = -150 m/s²,
Force on object A = ma = 5 x (-150) = -750N
Note, the force and acceleration of object A only last for 0.02s. The other object in the collision will have force of +750N for 0.02s (though generally it will have a different velocity change and acceleration to A’s).