Question

multiple select question
select all that apply
in which of the following situations is there a normal force acting on the object?
a thrown ball
a car on the highway
a sitting student
a falling apple
an airplane in flight
a hovering helicopter
a roller coaster car

Explanation:

A normal force is a contact force exerted by a surface perpendicular to itself on an object in contact with it.

• A thrown ball, falling apple, airplane in flight, and hovering helicopter are not in contact with a solid surface (ignoring air, which does not exert normal force), so no normal force acts on them.
• A car on the highway is in contact with the road surface, which exerts a normal force upward.
• A sitting student is in contact with a chair/ground, which exerts an upward normal force.
• A roller coaster car is in contact with its track, which exerts a normal force (direction varies with track position).

Answer:

B. A car on the highway
C. A sitting student
G. A roller coaster car