1. Suppose you want to demonstrate the Doppler effect for deep-water waves using a 2.50Hz source moving toward a stationary observer. How fast would the source have to move through the water if the frequency of the waves seen by the observer is to be 3.00 times the frequency of the source?

2. If two 82.0nC point charges exert a force of 1.10 N on each other, what is the distance between them?

3. If the electric field 0.210m from a point charge is 1.2810^4N/C, what is the magnitude of the charge?