An isotope decreased to one fourth its original amount in 18 months. What is the half life of this radioactive isotope?

A boy is running to the east and jumps into a stationary boat in a lake. Once the boy lands in the boat, the boat moves to the east.

A careless window washer dropped his water bucket from high up on the building. The sound of the bucket reached the window washer 4.7 seconds after he dropped it. If the speed of the sound that that day was 347m/s how high was the window washer

What protect and support the cell in a animal cell

Which sequence of coefficients will balance the following equation Ca (s) O2 (g) 2CaO (s)

Which of the following statements best describes the basic structure of an atom? a. Electrons and protons are in motion around a nucleus that contains neutrons. b. Neutrons are in motion around a nucleus that contains protons and electrons. c.

A tire swing is released from some initial height such that the speed of the tire at the bottom of the swing is 2.5 m/s. What is the initial height of the tire? Note: g = 9.8 m/s2 A 0.13m B 0.16m C 0.32m D 3.1 m

Paleoclimatologists study the climate and its changes throughout earths history. what observation by paleoclimatologists led scientists to predict that the average temperature of the planet is rising due to the combustion of fossil fuels?

Which is bigger, a kilometer or a mile?

A coach wants her team to have fun, win some games, and be a productive unit. What is the most important personality trait the coach should demonstrate to achieve her goals? sportsmanship leadership persistence discipline

You slide a box of books at constant speed up a 30° ramp, applying a force of 200 n directed up the slope. the coefficient of sliding friction is 0.18.