The radioactive isotope U-238 has protons and neutrons.

Aplayer uses a hockey stick to push a puck at a constant velocity across the ice. the weight of the puck is 170 n. the coefficient of friction is 0.0600. with what force must the player push the puck so that his force just equals the frictional force? 28.3 n 0.999 n 0.102 n 0.0104 n

Fossils have been found on two continents that are split apart, this is evidence that ? a. there was a bridge b. the continents were once joined together c. the life just appeared in two locations independently d. they swam across the ocean

Copper has a specific heat of 0.385 j. a piece of copper absorbs 5000 j of energy and undergoes a temperature change from 100 celsius to 200 degrees celsius. what is the mass of the piece of copper?