Question

Judy is pulling on a trunk with a 12-N force. Ike pulls at right angles to Judy. With how much force must Ike pull to make the resultant force on the trunk 20 N? Round answer to one decimal place.

Answer 1

Use the idea of summing vectors (forces in this case).
Since the forces form a nice triangle, we can quickly use Pythagoras theorem to solve this.
\[F_{result}=\sqrt{12^{2}+F_{Ike}^{2}}=20\]
Square both sides:
\[20^{2}=12^{2}+F_{Ike}^{2}\]
bring 12 squred to the other side and square rotting would give you the force required.