Commercial airplanes are sometimes pushed out of the passenger loading area by a tractor. (a) an 1800-kg tractor exerts a force of 1.75×104 n backward on the pavement, and the system experiences forces resisting motion that total 2400 n. if the acceleration is 0.150 m/s2 , what is the mass of the airplane? (b) calculate the force exerted by the tractor on the airplane, assuming 2200 n of the friction is experienced by the airplane. (c) draw two sketches showing the systems of interest used to solve each part, including the free-body diagrams for each

Consider a double atwood machine constructed as follows: a mass 4m is suspended from a string that passes over a massless pulley on frictionless bearings. the other end of this string supports a second similar pulley, over which passes a second string supporting a mass of 3m at one end and m at the other. using two suitable generalized coordinates, set up the lagrangian and use the lagrange equations to find the acceleration of the mass 4m when the system is released. explain why the top pulley rotates even though it carries equal weights on each side.

Why does karst topography exist in some geographic location? a. few climates have enough oxygen b. most regions have rock layers other than limestone c. in most regions, the soil is too thin d. the water is too acidic enough in most places

You can melt ice by applying pressure because the solid/liquid line has a slope.