CAIE A-Level Physics AS 4.2 Equilibrium of Forces Questions

Practise resolving forces, applying equilibrium and moments to determine unknown forces, angles or tensions in supported rigid bodies.

Exam points

resolve forces and use vector addition or a vector triangle to represent the resultant force
apply equilibrium conditions to determine unknown forces, angles or tensions in a system at rest
combine moments and force balance to analyse supported bodies, including non-uniform loads and contact forces

Covered syllabus points

4.2.1—The principle of moments 4.2.2—That, when there is no resultant force and no resultant torque, a system is 4.2.3—A vector triangle to represent coplanar forces in equilibrium

[Maximum number: 1]

The diagram shows a uniform rod, X Y, that is freely hinged to a vertical wall at end Y. The rod is at an angle of $60^{\circ}$ to the wall.

Figure for Question 1 — CAIE A-Level Physics AS

A force F acts at an angle of $30^{\circ}$ to the rod at end X. The rod has a weight of 3.0 N and is in equilibrium.

What is the magnitude of force F ?

$0.87 \mathrm{~N}$

$1.5 \mathrm{~N}$

$2.6 \mathrm{~N}$

$5.2 \mathrm{~N}$

[Maximum number: 1]

The total number of forces acting on an object is two. The object is in equilibrium.
Which statements about the forces are correct?

1 The two forces must have equal magnitudes.
2 The two forces must act in the same direction.
3 The two forces must act through the same point.

1 and 2 only

1 and 3 only

2 and 3 only

1, 2 and 3