Net force Knowledge-Based Practice

Questions

1. 1.

   Two forces given by $\vec{F}_1 = (7\hat{i} - 5\hat{j})$ N and $\vec{F}_2 = (5\hat{i} + 10\hat{j})$ N act simultaneously on an object. What is the magnitude of the net force acting on the object?

   • A) 7 N
   • B) 17 N
   • C) 13 N
   • D) 169 N
2. 2.

   A wagon on a level floor is pulled by a force of 20 N directed at an angle of 60° above the horizontal. If a friction force of 4 N opposes the forward motion, what is the magnitude of the net horizontal force acting on the wagon? (Take $\cos(60^\circ) = 0.5$.)

   • A) 16 N
   • B) 14 N
   • C) 10 N
   • D) 6 N
3. 3.

   Three forces of magnitudes 4 N, 6 N, and 10 N act concurrently on a particle such that the net force is zero. What is the angle between the 4 N force and the 6 N force?

   • A) 180°
   • B) 90°
   • C) 0°
   • D) 45°
4. 4.

   Which of the following statements correctly describes the direction of the net force acting on an object?

   • A) It is always in the same direction as the object's acceleration.
   • B) It is always in the same direction as the object's velocity.
   • C) It is always in the direction of the largest individual force acting on the object.
   • D) It is always opposite to the direction of motion whenever the object is in motion.
5. 5.

   A 20 kg crate is lifted vertically by a cable that exerts an upward tension force of 260 N. Taking the acceleration due to gravity as $9.8\text{ m/s}^2$, what is the magnitude of the net vertical force acting on the crate?

   • A) 64 N
   • B) 196 N
   • C) 260 N
   • D) 456 N
6. 6.

   Two mutually perpendicular forces act simultaneously on an object. If the magnitude of one force is 15 N and the magnitude of the net force acting on the object is 25 N, what is the magnitude of the second force?

   • A) 10 N
   • B) 16 N
   • C) 20 N
   • D) 40 N
7. 7.

   Which of the following sets of three concurrent forces cannot produce a net force of zero on an object, regardless of their directions?

   • A) 3 N, 5 N, and 7 N
   • B) 4 N, 4 N, and 4 N
   • C) 4 N, 6 N, and 10 N
   • D) 2 N, 6 N, and 9 N
8. 8.

   When two concurrent forces act in the same direction, the magnitude of their net force is 18 N, and when they act in opposite directions, the magnitude of their net force is 6 N. What is the magnitude of the larger individual force?

   • A) 9 N
   • B) 12 N
   • C) 15 N
   • D) 24 N
9. 9.

   Two forces, each having a magnitude of 10 N, act concurrently on an object with an angle of 120° between their directions. What is the magnitude of the net force acting on the object?

   • A) 0 N
   • B) 5 N
   • C) 10 N
   • D) 20 N
10. 10.

    Three coplanar forces of magnitudes 5 N, 12 N, and 13 N act simultaneously on a particle such that the overall net force on the particle is zero. What is the magnitude of the net force produced by the 5 N and 12 N forces alone?

    • A) 7 N
    • B) 17 N
    • C) 13 N
    • D) 0 N
11. 11.

    Two forces of constant non-zero magnitudes act simultaneously on an object. At what angle between their directions is the magnitude of the resulting net force maximized?

    • A) 180° (forces pointing in opposite directions)
    • B) 90° (forces pointing perpendicular to each other)
    • C) 45° (forces pointing at an acute angle)
    • D) 0° (forces pointing in the same direction)
12. 12.

    Four horizontal forces act simultaneously on an object: 7 N directed north, 3 N directed south, 8 N directed east, and 5 N directed west. What is the magnitude of the net force acting on the object?

    • A) 1 N
    • B) 5 N
    • C) 7 N
    • D) 23 N
13. 13.

    In which of the following situations is the net force acting on the object non-zero?

    • A) A crate sliding along a straight horizontal path at a constant speed
    • B) A picture frame hanging motionless on a vertical wall
    • C) A race car rounding a curved track at a constant speed
    • D) An airplane cruising along a straight horizontal path at a constant velocity
14. 14.

    Which of the following statements correctly defines the net force acting on an object?

    • A) It is the vector sum of all external forces acting on the object.
    • B) It is the scalar sum of the magnitudes of all forces acting on the object.
    • C) It is the difference between the greatest and smallest forces acting on the object.
    • D) It is the product of the total number of applied forces and their average magnitude.
15. 15.

    Two forces with magnitudes of 8 N and 14 N act simultaneously on an object. Which of the following could NOT be the magnitude of the net force acting on the object?

    • A) 7 N
    • B) 11 N
    • C) 19 N
    • D) 24 N
16. 16.

    A box subjected to two horizontal forces experiences a net force of 20 N directed to the right. If one of the forces is 35 N directed to the left, what is the magnitude and direction of the second force?

    • A) 15 N directed to the right
    • B) 15 N directed to the left
    • C) 55 N directed to the right
    • D) 55 N directed to the left
17. 17.

    A sled moves across a level frozen pond in a straight line at a constant speed of 5 m/s. What is the magnitude of the net force acting on the sled?

    • A) 5 N
    • B) 0 N
    • C) 10 N
    • D) 25 N
18. 18.

    An object moving along a straight track experiences three horizontal forces: a forward propulsion force of 50 N, a backward friction force of 30 N, and a backward air resistance force of 8 N. What is the magnitude of the net horizontal force acting on the object?

    • A) 88 N
    • B) 38 N
    • C) 28 N
    • D) 12 N
19. 19.

    A small cart on a smooth horizontal surface is pulled simultaneously by a 6 N force directed toward the north and an 8 N force directed toward the east. What is the magnitude of the net horizontal force acting on the cart?

    • A) 2 N
    • B) 7 N
    • C) 14 N
    • D) 10 N
20. 20.

    A crate on a frictionless horizontal floor is pulled simultaneously by a 14 N force to the east and an 8 N force to the west. What is the magnitude and direction of the net force acting on the crate?

    • A) 6 N to the west
    • B) 6 N to the east
    • C) 22 N to the east
    • D) 22 N to the west

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