Torque & Equilibrium Video Lessons

Video Thumbnail

Concept

Problem: A uniform 300-N trapdoor in a ceiling is hinged at one side.a) Find the net upward force needed to begin to open it, if the upward force is applied at the center of the edge opposite the hinges.b) Find the total force exerted on the door by the hinges, if the upward force is applied at the center of the edge opposite the hinges.

FREE Expert Solution

Torque:

τ=rFsinθ

Newton's second law: 

ΣF=ma

Let the length of the door be L.

(a)

The force applied acts at a distance L from the rotational point while the weight acts at L/2 from the hinges.

The forces and radial distance are perpendicular — θ = 90°

ΣT = 0

(L/2)•mgsin 90 - (L)Fapplied sin 90 = 0

View Complete Written Solution
Problem Details

A uniform 300-N trapdoor in a ceiling is hinged at one side.

a) Find the net upward force needed to begin to open it, if the upward force is applied at the center of the edge opposite the hinges.


b) Find the total force exerted on the door by the hinges, if the upward force is applied at the center of the edge opposite the hinges.

Frequently Asked Questions

What scientific concept do you need to know in order to solve this problem?

Our tutors have indicated that to solve this problem you will need to apply the Torque & Equilibrium concept. You can view video lessons to learn Torque & Equilibrium. Or if you need more Torque & Equilibrium practice, you can also practice Torque & Equilibrium practice problems.