A2,000 g quantity of c-14 is left to undergo radioactive decay. the half-life of c-14 is approximately 5,700 years. after going trough x half-lives, the sample becomes 125 grams. what is x?

Shelly experiences a backward jolt when the driver starts the school bus. which of the following explains this phenomenon? a. the inertia of shelly b. the inertia of the bus c. the normal force of the seats on shelly d. the net force acting on shelly in a backward direction e. a zero net force acting on shelly

This is for my 8th grade science class, i really don’t understand. can someone me? , lol.

A14 kg rock starting from rest free falls through a distance of 5.0 m with no air resistance. find the momentum change of the rock caused by its fall and the resulting change in the magnitude of earths velocity. earth mass is 6.0 * 10^24 kg. show your work assuming the rock earth system is closed.