The force of a plane's engine is moving the plane toward the right with 800N. Coming from the left you have resistance forces of air with 60N and friction with 40N. What is the direction and net forces that is being applied
the plane?

Consider a u-tube whose arms are open to the atmosphere. now equal volumes of water and light oil (ρ = 49.3 lbm/ft3) are poured from different arms. a person blows from the oil side of the u-tube until the contact surface of the two fluids moves to the bottom of the u-tube, and therefore, the liquid levels in the two arms are the same. if the fluid height in each arm is 30 in, determine the gage pressure exerted by the person on the oil by blowing.