Physics Grade 11
posted by Sybil .
12kg box is placed on a rough surface. A force of 20N is applied at an angle of 30 degrees. Calculate the magnitude and direction of the normal and friction forces

if no one has answered this question yet, that is means the question is difficult. So i will try if i know. I think the answer is 62

The normal force is always perpendicular to the surface. So if the box is on a horizontal surface the Normal force it will be equal to the weith of it (mass *gravity)
N= m*g N=117.6N the friction force always oposses to the movement and it will be equal to the horizontal component of the force that is F Cos 30ยบ
Fr= 20N*Cos 30 = 17.32 N