2. Forces in Equilibrium

Question 1

What does a free-body force diagram show?

Answer 1

The forces acting on a single body but not the forces it exerts on the rest of the world

Question 2

What does it mean if an object is in equilibrium?

Answer 2

All the forces acting on it are balanced and cancel each other out - there is no resultant force

Question 3

When only two forces are acting on a body, when is the body in equilibrium?

Answer 3

When the forces are equal and opposite

Question 4

What two ways is a body in equilibrium?

Answer 4

1. At rest

2. Moving at a constant velocity

Question 5

What do vectors drawn from tip to tail in a closed loop show?

Answer 5

The forces acting on a body cause it to be in equilibrium

Question 6

What are vectors drawn from tip to tail in a closed loop called?

Answer 6

1. A vector triangle

2. A vector polygon if more than 3 forces are involved

Question 7

How do you resolve forces of a body in equilibrium into its vertical and horizontal components?

Answer 7

1. The sum of the vertical components must sum to 0 (i.e. up + down = 0)
2. The sum of the horizontal components must sum to 0 (i.e left + right = 0)

Question 8

Name 2 methods to investigate equilibrium

Answer 8

1. Use a force board

2. Use pulleys and strings