A 10 kg box is resting on a smooth (frictionless) horizontal surface of a table. You pull the box by the attached ribbon with a force of 40 N at a 30 degrees angle from the surface of the table. Find the acceleration of the box and the magnitude of the normal force. Assume that friction can be neglected.
Draw a free-body diagram and identify all forces.
Find the sum of all forces in the horizontal (x) and vertical (y) direction and use Newton's 2nd law:
∑ Fx = 40N cos(30) = ma, a=40N cos(30)/10 kg = 3.5 m/s²
∑ Fy = 40N sin(30) +Fn -mg=0, Fn=mg - 40N sin(30) = 10(9.8) N - 20 N= 78 N