Combining Force Vectors
Finding the Resultant When Forces Act Together
A girl applies a 5 N east force on a dresser. Her brother also exerts a 5 N force. Why didn't the dresser move?
When doesn't 100 + 100 = 200?
Vector Addition - The Setup
Skip Right To The Answer
Video Instruction
showmethephysics.com
B. Combining Force Vectors
Resultant - single vector that will have the same effect as two or more vectors
1) Finding Resultants
Case I
Forces acting in same direction (Angle = 0 degrees)
Is resultant different than the one above?
RULE when θ = 0°
Add Forces
Case II
Forces acting in opposite direction (Angle = 180°)
If θ = 180°
Subtract smaller vector from larger
Check Your Understanding
5 quick questions — pick an answer to see if you’re right.
1. What is a resultant?
2. A 5 N force and a 4 N force both act east on a box. What is the resultant?
3. A 50 N force acts east and a 10 N force acts west on an object. What is the resultant?
4. A girl pushes a dresser 5 N east and her brother pushes with 5 N, but it doesn't move. What explains this?
5. What is the angle between two forces acting in opposite directions?
