1. Torque Wrench

2. Torque calculation
30cm
10N

3. Torque calculation 1

4. Torque calculation 1

5. Approaches to Torque Where is the pivot point?
What was the force applied?
How far from the pivot point was the force applied?
What was the angle for the direction of force?
Consider the sign conventions for the torque: Clockwise is NEGATIVE
Counterclockwise is POSITIVE
*do not blame me – I did not make it up!!!!

6. Torque calculation 2

7. Torque calculation 2

8. Torque calculation 3

9. Torque calculation 3

10. Ladder Problem Wall is frictionless Choose pivot at floor
Mass of ladder is 15kg
Θ = 60º
What μ is required at the floor to keep the
ladder from sliding when a 100kg painter
stands ¾ of the way up the ladder? Θ

11. Ladder Problem Mass of ladder is 15kg Θ = 60º
100kg painter stands ¾ up the ladder
Find μ FW WP V WL H
NOTE:
H = Ffr
V = FN = μFfr
Thus, μ = H/V

12. Ladder Problem Mass of ladder is 15kg Θ = 60º
100kg painter stands ¾ up the ladder
Find μ FW
Στ = 0
Στ = (Fwcos30)(L) – (980cos60)(3L/4) – (147cos60)(L/2)
0 = (0.866Fw) – 404
Fw = 467 N WP V WL H

13. Ladder Problem Mass of ladder is 15kg Θ = 60º
100kg painter stands ¾ up the ladder
Find μ FW
(Fw = 467 N from previous slide)
ΣFx = 0 = H – Fw = H - 467
Thus, H = 467 N
ΣFy = 0 = V – WL – Wp = V –
Thus, V = 1127 N
μ = H/V = 467/1127 = 0.41 WP V WL H