Why do astronauts need to wear pressurized suits in space?
a. because air pressure is so great in space they could be crushed without the suits.
b. because without the pressure in the suits the astronauts could freeze to death.
c. because space is a vacuum, the astronauts' bodies could explode without the suits.
d. the pressure protects them from solar radiation.

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.

An important dimensionless parameter concerned with very high-speed flow is the mach number, defined as v/c, where v is the speed of the object such as an airplane or projectile, and c is the speed of sound in the fluid surrounding the object. for a projectile traveling at 1170 mph through air at 50 ˚f and standard atmospheric pressure, what is the value of the mach number?

Directions: count the number of atoms. ar co2 na3po4 so3 nac2h3o2