Question

a force of 100n need to be applied parallel to a smooth inclined plane just to hold a body on it. the angle of inclination of the inclined plane is 30°. how much horizontal force need to be applied to do the same

Answer 1

a force of 100n need to be applied parallel to a smooth inclined plane just to hold a body on it. the angle of inclination of the inclined plane is 30°
Here we assume F acts horizontal force on block of mass m. for finding F

we have to resolve F in components , along parallel and perpendicular of plane.

so, Fcos30° = 100N
F = 100/cos30°

we know, cos30° = √3/2 = 0.866

so, F = 100/0.866 = 115.47 ≈ 115 N

hence, answer should be 115N