Free-body diagrams Knowledge-Based Practice

Questions

1. 1.

   A student holds a wooden block stationary by pressing downward on it with their hand, keeping a vertical spring beneath the block compressed against the floor. Which set of forces correctly represents all the individual forces that must be included in the free-body diagram of the block?

   • A) Downward gravitational force, upward pushing force from the hand, and downward elastic force from the spring
   • B) Downward gravitational force, downward pushing force from the hand, upward elastic force from the spring, and upward normal force from the floor
   • C) Downward gravitational force, downward pushing force from the hand, and upward elastic force from the spring
   • D) Downward pushing force from the hand and upward elastic force from the spring only
2. 2.

   A crate is held stationary on a frictionless inclined ramp by a horizontal pushing force. Which set of forces correctly represents all the individual forces that must be included in the free-body diagram of the crate?

   • A) A downward gravitational force, a normal force perpendicular to the ramp surface, the horizontal pushing force, and a downhill force parallel to the ramp
   • B) A downward gravitational force, a vertically upward normal force, and the horizontal pushing force
   • C) A downward gravitational force, a normal force perpendicular to the ramp surface, and the horizontal pushing force
   • D) A downward gravitational force, a normal force perpendicular to the ramp surface, the horizontal pushing force, and a static friction force parallel to the ramp
3. 3.

   A small ball attached to a light string moves in a horizontal circle at constant speed, forming a conical pendulum. Neglecting air resistance, which set of forces correctly represents all the individual forces acting on the ball that must be included in its free-body diagram?

   • A) The downward gravitational force and the tension force directed along the string
   • B) The downward gravitational force, the tension force directed along the string, and a centripetal force directed horizontally inward
   • C) The downward gravitational force, the tension force directed along the string, and a centrifugal force directed horizontally outward
   • D) The downward gravitational force, an inward horizontal force, and an outward horizontal force
4. 4.

   A block on a frictionless horizontal surface is attached to an ideal spring that is stretched to the right. Which set of forces correctly represents all the individual forces that must be included in the free-body diagram of the block immediately after it is released from rest?

   • A) A downward gravitational force, an upward normal force, a leftward spring force, and a leftward force of acceleration
   • B) A downward gravitational force and a leftward spring force only
   • C) A downward gravitational force, an upward normal force, and a leftward spring force
   • D) A downward gravitational force, an upward normal force, and a rightward restoring force
5. 5.

   A satellite travels at a constant speed in a circular orbit around Earth, with negligible atmospheric drag. Which set of forces correctly represents all the individual forces that must be included in the free-body diagram of the satellite?

   • A) A gravitational force directed toward the center of Earth and a forward force in the direction of motion
   • B) Only the gravitational force directed toward the center of Earth
   • C) A gravitational force directed toward the center of Earth and an outward centrifugal force
   • D) A gravitational force directed toward the center of Earth, an outward centrifugal force, and a forward tangential force
6. 6.

   A cart on a frictionless horizontal track is connected to a hanging weight by a light string that passes over a frictionless pulley. While the cart accelerates along the track, which set of forces correctly represents all the individual forces that must be included in the free-body diagram of the cart?

   • A) The downward gravitational force on the cart, the upward normal force from the track, the horizontal tension force from the string, and a forward accelerating force.
   • B) The downward gravitational force on the cart, the upward normal force from the track, and the horizontal tension force from the string.
   • C) The downward gravitational force on the cart, the upward normal force from the track, the horizontal tension force from the string, and the gravitational force of the hanging weight.
   • D) The downward gravitational force on the cart, the upward normal force from the track, and the gravitational force of the hanging weight acting horizontally.
7. 7.

   A skydiver falls vertically downward through the air at a constant terminal velocity. Which set of forces correctly represents all the individual forces that must be included in the free-body diagram of the skydiver?

   • A) A downward gravitational force, an upward air resistance force, and a downward force of motion
   • B) A downward gravitational force and an upward air resistance force
   • C) A downward gravitational force, an upward air resistance force, and a downward net force
   • D) A downward gravitational force only
8. 8.

   When constructing a free-body diagram for a chosen object, which forces should be represented as vectors acting on that object?

   • A) Only the forces that the object exerts on surrounding objects
   • B) Both the forces acting on the object and the reaction forces exerted by the object on other bodies
   • C) Only the external forces exerted directly on the object by its environment
   • D) The external forces acting on the object together with the resultant net force vector
9. 9.

   Two blocks, 1 and 2, rest in contact on a frictionless horizontal floor, and a person applies a constant horizontal pushing force to the right against block 1, accelerating both blocks. Which set of forces correctly represents all the individual forces that must be included in the free-body diagram of block 2?

   • A) A downward gravitational force, an upward normal force from the floor, and a horizontal contact force exerted by block 1 directed to the right
   • B) A downward gravitational force, an upward normal force from the floor, a horizontal contact force exerted by block 1, and the person's pushing force directed to the right
   • C) A downward gravitational force, an upward normal force from the floor, and the person's horizontal pushing force directed to the right
   • D) A downward gravitational force, an upward normal force from the floor, a horizontal contact force exerted by block 1, and a forward accelerating force
10. 10.

    A box rests on top of a crate, and both remain stationary on a level floor. Which set of forces correctly represents all the individual forces that must be included in the free-body diagram of the crate?

    • A) A downward gravitational force from Earth, a downward normal force exerted by the box, and an upward normal force exerted by the floor
    • B) A downward gravitational force from Earth and an upward normal force exerted by the floor only
    • C) A downward gravitational force from Earth, a downward gravitational force exerted by Earth on the box, and an upward normal force exerted by the floor
    • D) A downward gravitational force from Earth, an upward contact force exerted by the crate on the box, and an upward normal force exerted by the floor
11. 11.

    A traffic light hangs stationary above an intersection, supported entirely by two separate cables extending upward at angles to support poles. Neglecting air resistance, which set of forces correctly represents all the individual forces that must be included in the free-body diagram of the traffic light?

    • A) Downward gravitational force, tension force from the first cable, tension force from the second cable, and an upward equilibrant force
    • B) Downward gravitational force, an upward normal force, and tension force from each cable
    • C) Downward gravitational force and a single net upward tension force
    • D) Downward gravitational force, tension force from the first cable, and tension force from the second cable
12. 12.

    A bucket of water is hoisted vertically upward by a cable while accelerating upward. Neglecting air resistance, which set of forces correctly represents all the forces that must be included in the free-body diagram of the bucket?

    • A) An upward tension force from the cable and a downward gravitational force from Earth
    • B) An upward tension force from the cable, a downward gravitational force from Earth, and an upward force of acceleration
    • C) An upward tension force from the cable, a downward gravitational force from Earth, and a downward inertia force
    • D) Only an upward tension force from the cable because the bucket is accelerating upward
13. 13.

    A block is held stationary pressed against a flat, horizontal ceiling by a person exerting a steady upward vertical force that is greater than the block's weight. Which set of forces correctly represents all the individual forces that must be included in the free-body diagram of the block?

    • A) An upward applied force, a downward gravitational force, and an upward normal force exerted by the ceiling
    • B) An upward applied force, a downward gravitational force, and a downward normal force exerted by the ceiling
    • C) An upward applied force and a downward gravitational force only
    • D) An upward applied force, a downward normal force exerted by the ceiling, and a downward frictional force
14. 14.

    A car travels at a constant speed along an unbanked, horizontal circular road. Neglecting air resistance, which set of forces correctly represents all the individual forces that must be included in the free-body diagram of the car?

    • A) The downward gravitational force, the upward normal force, and the static friction force directed toward the center of the circle
    • B) The downward gravitational force, the upward normal force, the static friction force directed toward the center, and an outward centrifugal force
    • C) The downward gravitational force, the upward normal force, the static friction force directed toward the center, and an additional inward centripetal force
    • D) The downward gravitational force, the upward normal force, a forward propulsion force, and a backward kinetic friction force
15. 15.

    A wooden crate rests on the flat, horizontal bed of a truck that is accelerating forward along a straight road, and the crate does not slip. Neglecting air resistance, which set of forces correctly represents all the individual forces that must be included in the free-body diagram of the crate?

    • A) A downward gravitational force, an upward normal force, a forward force from the engine, and a backward static friction force
    • B) A downward gravitational force, an upward normal force, and a forward static friction force
    • C) A downward gravitational force, an upward normal force, and a backward static friction force
    • D) A downward gravitational force, an upward normal force, a forward static friction force, and a backward inertia force
16. 16.

    A baseball travels through the air along a curved trajectory after leaving the bat, with air resistance considered negligible. Which of the following correctly identifies all the forces that must be included in the free-body diagram of the baseball during flight?

    • A) The downward gravitational force and a forward contact force exerted by the bat
    • B) The downward gravitational force and a forward force acting along the direction of motion
    • C) The downward gravitational force only
    • D) The downward gravitational force, a forward force of motion, and an upward inertia force
17. 17.

    A small sphere attached to an ideal string swings through the lowest point of its vertical circular path. Which forces act on the sphere at this instant and must be included in its free-body diagram?

    • A) Downward gravitational force, upward tension force, and downward centripetal force
    • B) Downward gravitational force, upward tension force, and forward force of motion
    • C) Downward gravitational force and upward tension force only
    • D) Downward gravitational force, upward tension force, and upward centripetal force
18. 18.

    A wooden sled is sliding up a rough inclined ramp after being released from an initial push. Which set of forces correctly represents all the individual forces acting on the sled as it moves up the ramp?

    • A) A downward gravitational force, a normal force perpendicular to the ramp, a kinetic friction force down the ramp, and an applied force directed up the ramp
    • B) A gravitational force perpendicular to the ramp, a normal force directed vertically upward, and a kinetic friction force directed down the ramp
    • C) A gravitational force directed vertically downward, a normal force directed perpendicular to the ramp, and a kinetic friction force directed down the ramp
    • D) A gravitational force directed vertically downward, a normal force directed perpendicular to the ramp, and a kinetic friction force directed up the ramp
19. 19.

    A book is held stationary against a vertical wall by a person pressing horizontally against it. Which set of forces must be included in the free-body diagram of the book?

    • A) Gravitational force, applied pushing force, normal force from the wall, and static friction force from the wall
    • B) Gravitational force, applied pushing force, and normal force from the wall only
    • C) Gravitational force, applied pushing force, and static friction force from the wall only
    • D) Gravitational force, applied pushing force, normal force from the wall, and kinetic friction force from the wall
20. 20.

    A crate is pulled across a rough horizontal floor to the right at constant velocity by a horizontal rope. Which set of forces correctly represents all the individual forces that must be included in the free-body diagram of the crate?

    • A) Downward gravitational force, upward normal force, and rightward tension force only
    • B) Downward gravitational force, upward normal force, rightward tension force, and a rightward force of motion
    • C) Downward gravitational force, upward normal force, rightward tension force, and leftward kinetic friction force
    • D) Downward gravitational force, rightward tension force, and leftward kinetic friction force only

Answers and step-by-step solutions appear after you finish the test.