Q: Which condition must be satisfied for an object to be in static equilibrium?

$$\sum F = 0$$ and $$\sum \tau = 0$$

Q: Which scenario will maximize the torque produced by a force?

The force is applied perpendicular to the lever arm ($$\theta = 90^\circ).$$

Question 1

Which of the following best describes static equilibrium?

Accepted Answer

The sum of the forces and torques acting on an object is zero, and the object is not moving.

Question 2

A 5 kg mass is hung in the middle of a rope, which forms an angle $$	heta$$ with the horizontal on both sides. What is the tension $$T in $$each side of the rope?

Accepted Answer

$$T = \frac{Mg}{2\sin	heta}$$

Question 3

Which condition must be satisfied for an object to be in static equilibrium?

Accepted Answer

$$\sum F = 0$$ and $$\sum 	au = 0$$

Question 4

What is the definition of dynamic equilibrium?

Accepted Answer

An object is moving at a constant velocity and the sum of the forces acting on it is zero.

Question 5

A child sits on a swing hanging at rest. Which type of equilibrium is the swing in?

Accepted Answer

Static equilibrium

Question 6

If the sum of the forces acting on an object is zero, but the sum of the torques is not zero, what will happen?

Accepted Answer

The object will rotate.

Question 7

Which of the following best describes neutral equilibrium?

Accepted Answer

The object remains in its new position after being displaced.

Question 8

A force $$F is $$applied at a distance $$r$$ from the axis of rotation at an angle $$	heta. $$What is the torque $$	au$$?

Accepted Answer

$$	au = F r \sin	heta$$

Question 9

Which scenario will maximize the torque produced by a force?

Accepted Answer

The force is applied perpendicular to the lever arm ($$	heta = 90^\circ).$$

Question 10

What happens to an object in unstable equilibrium when it is slightly displaced?

Accepted Answer

It moves further away from its original position.

Question 11

A ladder is leaning against a wall. What must be true for the ladder to remain in static equilibrium?

Accepted Answer

The sum of the forces and the sum of the torques acting on the ladder must both be zero.

Question 12

If a car is moving at constant velocity, which type of equilibrium is it in?

Accepted Answer

Dynamic equilibrium

Question 13

A force of 10 N is applied at a distance of 2 m from the axis of rotation at an angle of $$90^\circ. $$What is the torque?

Accepted Answer

$$	au = 20 	ext{ Nm}$$

Question 14

Which of the following is NOT a requirement for static equilibrium?

Accepted Answer

The object must be moving at constant velocity.

Question 15

A seesaw is balanced with two children sitting at different distances from the pivot. What must be true for the seesaw to remain balanced?

Accepted Answer

The sum of the torques about the pivot must be zero.

Question 16

If an object is displaced and returns to its original position, what type of equilibrium is it in?

Accepted Answer

Stable equilibrium

Question 17

A book rests on a table. Which forces are acting on the book?

Accepted Answer

Gravity and the normal force

Question 18

What is the tendency of a force to rotate an object about an axis called?

Accepted Answer

Torque

Question 19

A mass is suspended from two ropes at equal angles. If the mass is increased, what happens to the tension in each rope?

Accepted Answer

The tension increases.

Question 20

Which of the following is a real-world example of unstable equilibrium?

Accepted Answer

A pencil balanced on its tip.

Equilibrium and Stability: Statics, Torque, and Types of Equilibrium

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