Forces & Free-Body Diagrams (College Board AP® Physics 1: Algebra-Based): Exam Questions

1 hour29 questions
1a
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3 marks

Describe three properties of free-body force diagrams.

1b
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1 mark

Suggest an appropriate way to label a force arrow on a free-body diagram.

1c
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3 marks

A coordinate system can be used to simplify the translation from a free-body diagram to an algebraic representation.

State three properties which must be valid for this coordinate system.

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2a
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4 marks

A force applied to an object has an effect on that object.

State the possible effects of forces when applied to an object.

2b4 marks

State the effect of the forces on the objects in the following scenarios.

  1. The thrust from an engine on a car

  2. The friction of the brakes on a car

  3. The gravitational pull of a star on a comet

  4. Two opposing forces pulling on the ends of a spring

2c
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3 marks

All forces can be categorized into two types of force.

Name these two types of force and give an example of each.

2d
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4 marks

Describe the behavior of electrostatic forces acting on charged particles.

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3a
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2 marks

State the two properties of a normal force.

3b
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1 mark

Describe in terms of vectors the net force on a system.

3c
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1 mark

State the condition required for a system to be in translational equilibrium.

3d
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3 marks

Two soccer players go to strike the ball at the same time, as shown in Figure 1. One applies a force of 80 space straight N to the right and the other a force of 130 space straight N to the left.

Two players kick a football with forces of 80 N and 130 N. The player on the left kicks right, and the player on the right kicks left.

Figure 1

Identify whether or not the ball will be in translational equilibrium when in contact with both soccer players. Justify your reasoning.

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4a
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1 mark

Define translational equilibrium.

4b
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3 marks

State and explain whether an object moving at a constant velocity is in translational equilibrium.

4c
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3 marks

A box is being pulled along a flat horizontal surface with a string that applies a force of tension F subscript T at an angle theta to the horizontal. Kinetic friction F subscript f comma k end subscript acts between the box and the surface in the opposite direction to motion.

Draw a vector force diagram showing the forces acting on the box when it is in translational equilibrium.

4d
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5 marks

State the equation that represents the sum of the forces exerted on a system when they sum to zero. Explain what the symbols in the equation represent.

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1a
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3 marks

A box of mass m is placed on a rough horizontal surface. A person applies a force of F at an angle of theta above the horizontal.

Draw and label a free-body diagram of the box.

1b
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3 marks

Derive an expression for the normal force acting on the box in terms of theta.

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2
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3 marks
Pulley system with two suspended masses labeled "m1" on the left and "m2" on the right, connected over a central pulley wheel.

Figure 1

Two blocks are connected by a light string that passes over a frictionless pulley of negligible mass, as shown in Figure 1. The masses of the two blocks are m subscript 1 and m subscript 2 respectively, where m subscript 2 space greater than space m subscript 1.

The dots below represent the blocks. Draw and label arrows that represent the forces (not components) that are exerted on the blocks. Each force must be represented by a distinct arrow starting on and pointing away from the appropriate dot. The relative lengths of the arrows should reflect the relative magnitudes of the forces.

Two grids, labeled Block of Mass m1 (left) and Block of Mass m2 (right), each with a black dot at the center.

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3a
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3 marks

A box of mass m is pulled across a rough horizontal surface by a constant applied force of magnitude F subscript A at an angle of 30 degree above the horizontal. The frictional force exerted on the box is F subscript f.

The dot below represents the box. Draw and label arrows that represent the forces (not components) that are exerted on the box. Each force must be represented by a distinct arrow starting on and pointing away from the dot. The relative lengths of the arrows should reflect the relative magnitudes of the forces.

A single black dot at the center of a 10 by 10 grid.
3b
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1 mark

Determine an expression for the net force exerted on the box in terms of F subscript A and F subscript f.

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4
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2 marks

A projectile is fired from level ground with speed v subscript 0 at an angle theta space greater than space 45 degree to the ground. The projectile is fired from a few centimeters before position x subscript 1, reaches its maximum height at position x subscript 2, and lands on the ground at position x subscript 3. end subscript.

Graph showing acceleration versus time. Vertical axis labelled 'a', horizontal 't'. Horizontal line at a = 0 labelled ax. Horizontal line at a = -10 labelled ay.

Figure1

Figure 1 is a graph of vertical and horizontal components of the acceleration of the projectile.

Diagram showing a dot with two arrows: one labelled 'F' pointing right, the other 'F₉' pointing downward, illustrating forces acting on an object.

Figure 2

A student sketches the free-body diagram shown in Figure 2, and makes the following claim:

"The free-body diagram shows the forces acting on the projectile at position x subscript 1. "

Justify why the student's sketch (Figure 2) and claim are not consistent with the graph in Figure 1.

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52 marks

A small object of mass m is attached to a string of variable length L and set into a conical pendulum motion, where the object moves in a horizontal circular path while the string traces out a cone as shown in Figure 1. The system allows for adjustment of the string length L and measurement of the angular velocity omega of the object.

A diagram showing a right triangle above a horizontal circle, with labelled angle to the vertical theta, radius r, hypotenuse h, and mass m inside the circle.

Figure 1

Draw and label arrows that represent the forces (not components) that are exerted on the object as it rotates in a horizontal circle, which is indicated by the dashed line. Each force in your diagram must be represented by a distinct arrow starting on, and pointing away from, the point at which the force is exerted on the object m.

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1
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3 marks
Dashed circle with radius lines AB and another line forming a 30-degree angle at a point on the circle, showing rotational direction.

Figure 1

A ball of mass m is attached to a string of length L and swings with constant speed in a vertical circle, as shown in Figure 1. At Point A, the ball passes the lowest point in its path, and at Point B, it makes an angle of 30 degree with the horizontal.

The dots below represent the ball at points A and B. Draw and label the forces (not components) that act on the ball at each point. Each force must be represented by a distinct arrow starting on and pointing away from the appropriate dot. The relative lengths of the arrows should reflect the relative magnitudes of the forces.

Two grids, labeled Point A (left) and Point B (right), each with a black dot at the center.

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2
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2 marks

A block is pushed along a rough horizontal surface with a horizontal force F subscript A.

Draw a free-body diagram of the forces acting on the block.

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3
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2 marks

A car travels around a banked curve at a speed slower than the ideal speed for the given banked angle.

Draw a free-body diagram for the car on the banked curve.

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4
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2 marks

A car travels around a banked curve where the banking angle is shallower than the ideal angle for the given speed, meaning friction is required to keep the car on the curve.

Draw a free-body diagram indicating all forces acting on the car, including friction.

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5
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3 marks

A student pushes a wooden box of mass m up a rough inclined plane at a constant velocity. The incline makes an angle theta to the horizontal, and the coefficient of kinetic friction between the box and the surface ismu subscript k​.

The box is pushed a distance d up the incline by a constant force F subscript a p p end subscript​ applied parallel to the surface.

On Figure 1, draw a free-body digram and label the arrows that represent the forces (not components) exerted on the box.

A box on an inclined plane with angle theta between the plane and the horizontal axis.

Figure 1

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