17. elaine connects an ammeter to a lamp, which is connected to a battery. she records the current. she connects another battery in series to the circuit and records the ammeter reading again. she repeats this step two more times.

a) which variable is elaine not changing?
b) which variable is elaine changing?
c) which variable is elaine studying?
d) what do you expect elaine's readings to show?

18. mary measures the current in a long, thin extension cord. she unplugs the cord and switches it for a shorter, thicker one. what will mary observe if she measures the current through the new extension cord?

The image shows the positions of a car on a roller coaster track. arrange the cars in order based on their gravitational potential energy. begin with the lowest potential energy and end with the highest.

Agroup of students is studying convection currents. they fill two identical balloons with the same amount of helium. one balloon is placed in a freezer and the other in an area with warm air. after 10 minutes, the balloons are released from a height of 1 meter. which of the following do the students most likely observe? question 2 options: the balloons rise at the same rate. both balloons are the same size. the ballons both rise. the cold ballon is larger than the warm balloon. the cold balloon expands and rises. the warm balloon shrinks and sinks. the warm balloon expands and rises. the cold balloon shrinks and sinks.

Asatellite component is in the shape of a cube with 10cm edges, has an evenly distributed mass of 2 kg and one bolt hole at each of four corners. if the maximum predicted random vibration environment is 10 grms, what bolt size would be a good choice for restraint? what other factors might drive bolt size besides force/stress?