In each question write down the value of component X 8N X 80 o

In each question write down the value of component X 5N X 20 o

In each question write down the value of component X 7N X 18 o

In each question write down the value of component X 4N X 70 o

In each question write down the value of component X 12N X 15 o

In each question write down the value of component X 30N X 50 o

In each question write down the value of component X 8N X 15 o

In each question write down the value of component X 25N X 40 o

In each question write down the value of component X 12N X 70 o

In each question write down the value of component X 40N X 130 o

In each question write down the value of component X 25N X 150 o

The Mechanics of Forces Lesson Objective: Understand Newton’s first law and be able to solve problems involving objects in equilibrium

Newton’s first law: Every body continues in a state of rest or in a state of uniform motion in a straight line unless acted on by a resultant force A body that exhibits this type of behaviour is said to be in equilibrium

Key aspects for solving problems involving objects in equilibrium: 1)Always draw a clear diagram of the objects 2)Add all the forces acting on the objects to the diagram 3)Write down equations for each separate object by resolving the forces on each object in two perpendicular directions 4)Look at all the equations you have written down and solve them simultaneously to answer the question Note: In essence we will do this same procedure for every type of question involving forces. As the situations become more complicated (not in equilibrium for example) the equations we write down will just be adjusted as necessary.

10 N 7 NA ? B ? What can you say about the size of forces A and B? A particle resting in equilibrium with 4 forces acting on it:

30 o What can you say about the size of forces A and B now? 10 N 7 NA ? B ? A particle resting in equilibrium with 4 forces acting on it:

60 o What can you say about the size of forces A and B now? 10 N 7 N A ? B ? A particle resting in equilibrium with 4 forces acting on it: 45 o

60 o 8 N 4 N A ? B ? 30 o 60 o B ? 4 N A ? 45 o 40 o B ? A ? 15 N 30 o θoθo 5 N 12 N 30 o 60 o

A particle is in equilibrium under the action of the forces shown. Find the magnitude of the forces P and S.

The forces in the diagram below are in equilibrium. Find R and θ.

The forces below are in equilibrium. Find the magnitude of P and Q