Resultant of Forces at Right Angles
When two forces P and Q act at right angles to each other, the resultant of these forces can be calculated using the Pythagorean theorem. This is a common scenario in mechanics and engineering, where forces often act in different directions.

Calculating the Resultant
To determine the resultant of forces P and Q, we can use the following formula:
R = √(P^2 + Q^2)
This formula is derived from the Pythagorean theorem, where the resultant force R is the hypotenuse of a right-angled triangle formed by forces P and Q.

Example
For example, if force P has a magnitude of 5 N and force Q has a magnitude of 12 N, the resultant force R can be calculated as follows:
R = √(5^2 + 12^2) = √(25 + 144) = √169 = 13 N
Therefore, the resultant force when forces P and Q act at right angles to each other is 13 N.

Vector Representation
In terms of vector representation, forces P and Q can be represented as vectors with their respective magnitudes and directions. The resultant force R is then the vector sum of these two forces, taking into account both magnitude and direction.

Conclusion
In conclusion, when two forces P and Q act at right angles to each other, the resultant force can be calculated using the Pythagorean theorem. This allows engineers and physicists to analyze and predict the overall effect of multiple forces acting on a system.