Two crates, a and b, sit at rest side by side on a frictionless horizontal surface. the crates have masses ma and mb. a horizontal force f is applied to crate a and the two crates move off to the right. draw the free-body diagram for crates a and b.

i have tried < --|> ; < --|--> ; < |--> to no avail, they are all incorrect. normal force up is equal to weight (gravity) force down so sum of vertical forces f = 0n. i know i am doing something wrong but cannot figure out what and the system does not point me in the write direction with each incorrect response.

Which of the following are used in an electrochemical cell? a. electrodes b. electrolyte c. terminals d. all of the above

To place a communications satellite into a geosynchronous orbit at an altitude of 22,240 mi above the surface of the earth, the satellite first is released from a space shuttle , which is in a circular orbit at an altitude of 185 mi, and then is propelled by an upper-stage booster to its final altitude. as the satellite passes through a, the booster's motor is fired to insert the satellite into an elliptic transfer orbit. the booster is again fired at b to insert the satellite into a geosynchronous orbit. knowing that the second firing increases the speed of the satellite by 4810ft/s, determine (a.) the speed of the satellite as it approaches b on the elliptic transfer orbit, (b.) the increase in speed resulting from the first firing at a.

Arock,thrown straight up, takes 4.2 seconds to reach its max height (g=9.8m/s) what was the initial velocity? what was its maximum height?