GED Science TestPhysical ScienceMedium
A student pushes a 10 kg box across a floor with a constant force of 50 N. If the frictional force opposing the motion is 20 N, what is the net force acting on the box?
- A50 N
- B20 N
- C70 N
- D30 N
Show answer & explanationAnswer & explanation
Correct answer: D. 30 N
Net force is the vector sum of all forces acting on an object. In this case, the applied force is 50 N in one direction, and the frictional force is 20 N in the opposite direction. Therefore, the net force is 50 N - 20 N = 30 N.
Why the other options are wrong
- A. This is the applied force, not the net force.
- B. This is the frictional force, not the net force.
- C. This would be the result if the forces were added, which is incorrect for opposing forces.
Net Force
Net force is the overall force acting on an object, which is the vector sum of all individual forces acting on it. It determines the object's acceleration.
- Vector sum of all forces
- Determines acceleration (F_net = ma)
- Forces in opposite directions subtract, forces in same direction add
Memory trick: Net Force: The Tug-of-War Total.