NRamp Force Problem: Find F and Normal Force on 87kg Crate

[Amberosia]

Homework Statement

a crate of mass m = 87 kg is pushed at a constant speed up a frictionless ramp (θ = 29°) by a horizontal force F. The positive direction of an x-axis is up the ramp, and the positive direction of a y-axis is perpendicular to the ramp. (a) What is the magnitude of F? What is the magnitude of the normal force on the crate?

Homework Equations

I'm not sure I know F=ma

The Attempt at a Solution

I know gravitational force=mg cos(theta)=87(9.8)(cos(29))=745.7

 

[kjohnson]

Actually the gravitational force is simply m*g and acts straight down. You are trying to find the two components of the gravitation force or weight in the directions of the shifted x,y coordinates. These components are usually called the perpendicular force 'Fy' and the parallel force 'Fx' (because one acts parallel to the incline and the other perpendicular).

So when you said you calculated the gravitational force you really calculated 'Fy'. Next calculate 'Fx'...

Last you need to sum forces in the x & y directions to solve for your unknowns.