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

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

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

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

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 and respectively, where .

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.

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

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.

Determine an expression for the net force exerted on the box in terms of and .

A projectile is fired from level ground with speed  at an angle  to the ground. The projectile is fired from a few centimeters before position , reaches its maximum height at position , and lands on the ground at position .

Figure1

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

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 . "

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

A small object of mass is attached to a string of variable length 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 and measurement of the angular velocity of the object.

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 .

Figure 1

A ball of mass is attached to a string of length 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 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.

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

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

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.

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.

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

The box is pushed a distance up the incline by a constant force ​ applied parallel to the surface.

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

Figure 1