Which is a safer car bumper in a collision: one that is flexible and retracts or one that is rigid? why? which is a safer car bumper in a collision: one that is flexible and retracts or one that is rigid? why? the retractable bumper, because softer things withstand collisions better. the rigid bumper, because it does not change shape so easily. the retractable bumper, because it extends the time interval of the collision, thus reducing the force exerted on the car.

As per Newton's II law we know that

now we know that

now we can say that force due to collision will be more if the interval of time for the collision is very small

so here in order to have safe collision we need to reduce the force due to collision

So we need to increase the time interval of collision

So correct answer here will be given as

The retractable bumper, because it extends the time interval of the collision, thus reducing the force exerted on the car.

i don't know that i agree with that but what's the question ?

the answer is 3.1 his answer is wrong mines is right