Why is it that the restoring force comes into action only after the applied external force is removed, from an elastic body?

Animals respond in various ways to stimuli detected through their senses. some of these responses are stimulated by the presence of danger. which of these animal responses is the best example of a response to an immediate threat? a) a rooster crows every morning at the first sign of light. b) as something approaches an octopus, it shoots a cloud of ink. c) from late fall until spring, bears hibernate to preserve energy. reactivate d) a dog is getting hot in the sunlight, so he moves to a shaded area.

What is the earliest point in the universe that we can observe? why can’t we see back further than this?

What happens to an isotope during radioactive decay?