You push against a steamer trunk with a force of 750 N at an angle of 25° with the horizontal. The trunk is on a flat floor and the coefficient of static friction between the trunk and floor is 0.77. What is the most massive trunk you will be able to move?

This means that the horizontal force is 750sin (25°). To be able to move the truck, force applied must be greater than static friction, which equals to its coefficient (0.77) x normal contact force ( = weight)

Hence, 750sin (25°) = 0.77mg. m = 750sin (25°) / (0.77g)