Physics help from experts.
Net force is the vector sum of all forces acting on an object. It is the resultant force left after opposing forces have cancelled out. Net force is the single force that produces the effect of all forces on an object combined. This unbalanced force produces the object's acceleration. An object that is not accelerating is experiencing a net force of zero.
Torque: when opposing forces act on different parts of an object, rather than cancel, they may change the object's rate of spin. In most situations in introductory courses, all forces act as though they are applied to one spot, the object's center of mass.
Which of the following objects is experiencing a non-zero net force?
a. a person standing on a floor?
b. a downhill skier angling across a slope with constant velocity
c. a planet circling the sun with constant speed
d. none of the above.
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