On August 27, 2003, Mars reached a distance of 55,758,000 km from the earth, which was the closest distance between the two planets in nearly 60,000 years. Which of the following values would you use to write
this distance in scientific notation to two significant figures?
O 56.0 x 106 km
O 5.6 x 108 km
O 5.6 x 107 km
O 5.5 x 107 km
O 5.57 x 108 km
5.57 x 107 km

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.

Apulley with mass mp and a radius rp is attached to the ceiling, in a gravity field of 9.81 m/s2 and rotates with no friction about its pivot.

A100-watt light bulb illuminates a solar cell. the electricity from the solar cell operates a water pump that delivers 1 watt of power. what is the efficiency of the system?