What Is the Correct Formula for Normal Force on a Sloped Surface?

[Robertoalva]

1. A skier of mass 51.4 kg comes down a slope of constant angle 26◦ with the horizontal. What force normal to the slope is exerted by the skis (neglect friction)? The acceleration of gravity is 9.8 m/s^2.

Homework Equations

F=ma

The Attempt at a Solution

my intuitions tell me to do this:

F=m*g*cos26

am i wrong?

 

[Robertoalva]

i already did this!

 

[PeterO]

1. A skier of mass 51.4 kg comes down a slope of constant angle 26◦ with the horizontal. What force normal to the slope is exerted by the skis (neglect friction)? The acceleration of gravity is 9.8 m/s^2.

Homework Equations

F=ma

The Attempt at a Solution

my intuitions tell me to do this:

F=m*g*cos26

am i wrong?

A hint on how to think:

The answer is either m*g*cos26 or m*g*sin26

Suppose the slope was ≈ 0 degrees; one of m*g*cos0 or m*g*sin0 is zero.

If the slope was ≈ 0 degrees, would the normal force be ≈ 0 ?

That shows which one is NOT the answer.