A force F pushes on a 25 kg box as shown in the figure. (a) The coefficient of static friction between box and incline is us = 0.20. How large a horizontal force must push on the block if the block is to be on the verge of sliding up the incline? 25 kg 40. 40 (b) A force F applied to an object of mass mi produces an acceleration of 3 m/s?. The same force applied to a second object of mass m2 produces an acceleration of 1 m/s?. If m and m2 are combined, find their acceleration under the action of the force F?

A force F pushes on a 25 kg box as shown in the figure. (a) The coefficient of static friction between box and incline is us = 0.20. How large a horizontal force must push on the block if the block is to be on the verge of sliding up the incline? 25 kg 40. 40 (b) A force F applied to an object of mass mi produces an acceleration of 3 m/s?. The same force applied to a second object of mass m2 produces an acceleration of 1 m/s?. If m and m2 are combined, find their acceleration under the action of the force F?