A sample of radioactive material emits 400 000 particles over a period of 20 minutes. Calculate the activity of the source in Becquerel (Bq).

In a heat engine if 1000 j of heat enters the system the piston does 500 j of work, what is the final internal energy of the system if the initial energy was 2000 j? 1. write the equation 2.list out your known variables 3.plug the numbers into the equations 4.solve 5.write your solution statement that includes initial energy and final

For waves in the ocean, the medium of the waves is a. air b. water c. energy d. a passing boat

Decreased sensitivity to an unchanging stimulus is known as