Vectors and equilibrium

Two perpendicular vectors of magnitude 3 and 4 are added. The magnitude of the resultant is:

• 1 1
• 2 7
• 3 5
• 4 12

The dot product of two perpendicular vectors is:

• 1 Infinite
• 2 1
• 3 0
• 4 Their product

The magnitude of the cross product of two parallel vectors is:

• 1 A B
• 2 1
• 3 A + B
• 4 Zero

A force of 10 N acts at 30 degrees to the horizontal. What is its horizontal component?

• 1 5 N
• 2 10 N
• 3 17.3 N
• 4 8.7 N

The first condition of equilibrium states that:

• 1 The net force is zero
• 2 Mass is constant
• 3 The net torque is zero only
• 4 Speed is always zero