What is the magnitude of the acceleration that is produced when the brakes of a 2.4 x 10 cubed kg car apply a 3.2 x 10 cubed N force to stop the car

Americium-241 undergoes fission to produce three neutrons per fission event. if a neutron-absorbing material is mixed in with this sample so that the rate of neutron production drops down to 1.8 neutrons per fission event, which will be effective at achieving a critical mass? check all that apply. remove a deflective shield surrounding the sample. remove absorbent material mixed in with the sample. compress the sample of americium-241.