Bob is pulling a 30 kg filing cabinet with a force of 200 n, but the filing cabinet refuses to move. the coefficient of static friction between the filing cabinet and the floor is 0.80. what is the magnitude of the friction force on the filing cabinet?

The force of friction is equal to the normal force multiplied by the coefficient of friction. In this case, the normal force is the force of gravity. F=ma, where m is the mass of the object and a is acceleration. The acceleration due to gravity is 9.8 m/s^2. Therefore F= 30kg *9.8m/s^2 = 294n. (1n = 1kgm/s^2). friction force = normal force * coefficient of friction friction force = 295n * 0.80 = 235.2n