Samarium has a half-life of approximately 106 billion years. If you found a sample of samarium from the beginning of Earth's history, approximately 4.6 billion years ago, which would be the best approximation of the amount of parent isotope left in the rock?

Acentrifuge in a medical laboratory rotates at an angular speed of 3,700 rev/min. when switched off, it rotates through 54.0 revolutions before coming to rest. find the constant angular acceleration (in rad/s2) of the centrifuge. your response is within 10% of the correct value. this may be due to roundoff error, or you could have a mistake in your calculation. carry out all intermediate results to at least four-digit accuracy to minimize roundoff error. rad/s2