Because energy is conserved, we can calculate kinetic or potential energy at all times if we know one or the other at different times. For example, if a car on a roller coaster has 1000J of potential energy when its parked at the top of the ride, and later it only has 100J of potential energy, we know that it must have 1000-100=900 joules of Potential energy at that later time. If the car has 250J of potential energy at some point in the ride, how much kinetic energy does it have?

a
750
b
100
c
850
d
7
e
200

The biologist has a second culture to examine. she knows that the population of the culture doubles every 15 minutes. after 1 hour and 15 minutes, her assistant found that 80,000 bacteria were present. a) what was the size of the initial population? b) predict the size of the culture at t=3 hours. what was the size of the population at 40 minutes? explain and justify your answers. c) create a graph of the population as a function of time. find an equation that can be used to predict the size of the population at any time t. d) examine the rate at which the bacteria culture is growing. how fast is the culture growing after 1 hour? after 1.5 hours? after 2 hours? use a time interval of h = 0.01 hours to estimate these rates. interpret these rates in terms of the context of the problem situation. how do these three rates compare?