Will the Block Slide Down a 30° Ramp with High Friction?

[Kytte]

Homework Statement

A 20.0kg block is placed onto a 30.0°ramp with a coefficient of static friction of0.850. Will the block slide down the ramp?

a) - if the block slides down the ramp, what is the minimum applied force needed to keep the block stationary?
- if the block does not slide down the ramp, what is the minimum applied force needed to start the block stationary?

Homework Equations

a=Fnet/m |F_f|= µ |F_N| g= Fg/m

The Attempt at a Solution

Fnet= F_f + Fg_//
ma= (mu)mg(cosθ) + mg(sinθ)
a= [(.85)(20kg)(p.81m/s²)(cos30°) + (20kg)(-9.81m/s²)(sin30°)]/20kg





supposedly the answers are [stationary] and [-46.3N]

 

[tiny-tim]

Welcome to PF!

Hi Kytte! Welcome to PF!

(have a mu: µ anad a degree: ° )

Show us what you've tried, and where you're stuck, and then we'll know how to help!

 

[Kytte]

Hi Kytte! Welcome to PF!

(have a mu: µ anad a degree: ° )

Show us what you've tried, and where you're stuck, and then we'll know how to help!

ok thank you!