6.9.1 The Conditions for Static Equilibrium

Question 1

The Conditions for Static Equilibrium

Answer 1

• An object is in equilibrium if the net force and net torque on it are zero. An object that is in equilibrium and also at rest is in static equilibrium.
• An object can be in either stable equilibrium or unstable equilibrium depending on its behavior when displaced from its equilibrium position. If the object returns to the position when displaced, it is in stable equilibrium; if it accelerates away,it is in unstable equilibrium

Question 2

A picture with a mass of 5.0 kg hangs motionless on a wall. Which of the following is the magnitude of the tension in the wires?

Answer 2

34.6 N

Question 3

Which of the following is not correct?

Answer 3

If an object is in equilibrium, then it is at rest.

Question 4

If a bar is in rotational equilibrium, then ________________.

Answer 4

the sum of the clockwise torques equals the sum of the counterclockwise torques

Question 5

In regards to the mechanical equilibrium, which of the following is not correct?

Answer 5

When the vector sum of all forces acting on a body is zero, we can say that the body is in mechanical equilibrium.

Question 6

A 5-N force balances a 10-N force on a lever. The torque due to the 5-N force must be __________________.

Answer 6

equal in magnitude to the torque due to the 10-N force

Question 7

Which of the following statements concerning static equilibrium is not correct?

Answer 7

If the sum of the torques that tend to produce clockwise rotation about any point is equal to the sum of the torques that tend to produce counterclockwise rotation, then the body is in static equilibrium.

Question 8

This question is related to the second condition for mechanical equilibrium, rotational equilibrium. Which of the following is not correct?

Answer 8

If a body is in rotational equilibrium, then there is a specific point where the sum of the torques must be zero.