The First Condition for Equilibrium Quiz
The question sheet
Reveal any answer as you study-
What is the first condition necessary to achieve equilibrium?
- Velocity must be zero
- Net torque must be zero
- Net external force must be zero
- Acceleration must increase
Reveal answer
Answer: Net external force must be zero
Source evidence
PDF page 400: The first condition necessary to achieve equilibrium is the one already mentioned: the net external force on the system must be zero. Expressed as an equation, this is simply 9.1 Note that if net is zero, then the net external force in any direction is zero. For example, the net external forces along the typical x- and y-axes are zero. This is written as 9.2
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A motionless person with forces adding to zero is an example of what?
- Static equilibrium
- Free fall
- Dynamic equilibrium
- Rotational motion
Reveal answer
Answer: Static equilibrium
Source evidence
PDF page 400: for both static equilibrium (motionless), and dynamic equilibrium (constant velocity).
PDF page 400: FIGURE 9.2 This motionless person is in static equilibrium. The forces acting on him add up to zero. Both forces are vertical in this case.
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A car moving at constant velocity is an example of what?
- Dynamic equilibrium
- Acceleration
- Static equilibrium
- Free fall
Reveal answer
Answer: Dynamic equilibrium
Source evidence
PDF page 400: for both static equilibrium (motionless), and dynamic equilibrium (constant velocity).
PDF page 401: FIGURE 9.3 This car is in dynamic equilibrium because it is moving at constant velocity. There are horizontal and vertical forces, but the net
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According to the source, dynamic equilibrium refers to motion at what?
- Constant acceleration
- Increasing speed
- Zero velocity
- Constant velocity
Reveal answer
Answer: Constant velocity
Source evidence
PDF page 400: for both static equilibrium (motionless), and dynamic equilibrium (constant velocity).
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For the person in Figure 9.2, both forces acting on him are in what orientation?
- Vertical
- Diagonal
- Horizontal
- Circular
Reveal answer
Answer: Vertical
Source evidence
PDF page 400: FIGURE 9.2 This motionless person is in static equilibrium. The forces acting on him add up to zero. Both forces are vertical in this case.
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In the car example, the applied force between tires and road is balanced by what?
- Normal force
- Air friction
- Torque
- Weight
Reveal answer
Answer: Air friction
Source evidence
PDF page 401: external force in any direction is zero. The applied force between the tires and the road is balanced by air friction, and the weight of the car is supported by the normal forces, here shown to be equal for all four tires.
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In the car example, the weight of the car is supported by what?
- Torque
- Normal forces
- Air friction
- Applied force
Reveal answer
Answer: Normal forces
Source evidence
PDF page 401: external force in any direction is zero. The applied force between the tires and the road is balanced by air friction, and the weight of the car is supported by the normal forces, here shown to be equal for all four tires.
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In the hockey stick example of Figure 9.4, friction is described as what?
- Constant
- Negligible
- Increasing
- Maximum
Reveal answer
Answer: Negligible
Source evidence
PDF page 401: FIGURE 9.4 An ice hockey stick lying flat on ice with two equal and opposite horizontal forces applied to it. Friction is negligible, and the
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In Figure 9.4, the gravitational force on the stick is balanced by what?
- Support of the ice
- Applied force
- Air friction
- Rotation
Reveal answer
Answer: Support of the ice
Source evidence
PDF page 401: FIGURE 9.4 An ice hockey stick lying flat on ice with two equal and opposite horizontal forces applied to it. Friction is negligible, and the
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The two horizontal forces applied to the hockey stick in Figure 9.4 are what?
- Both rightward
- Perpendicular
- Equal and opposite
- Unequal
Reveal answer
Answer: Equal and opposite
Source evidence
PDF page 401: FIGURE 9.4 An ice hockey stick lying flat on ice with two equal and opposite horizontal forces applied to it. Friction is negligible, and the
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In Figure 9.5, when forces are applied at other points, the stick does what?
- Stays motionless
- Rotates with acceleration
- Slows down
- Moves in a line
Reveal answer
Answer: Rotates with acceleration
Source evidence
PDF page 401: FIGURE 9.5 The same forces are applied at other points and the stick rotates—in fact, it experiences an accelerated rotation. Here
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According to Figure 9.5, the first condition is a necessary but not what?
- Static condition
- Vector condition
- Equal condition
- Sufficient condition
Reveal answer
Answer: Sufficient condition
Source evidence
PDF page 401: but the system is not at equilibrium. Hence, the is a necessary—but not sufficient—condition for achieving equilibrium.
AP College Physics
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