Question

1 multiple choice 2 points
a man weighing 800 newtons is standing on a chair. in order to support the man,
the chair is exerting a force of
0 newtons
400 newtons
800 newtons
8,000 newtons

2 multiple choice 2 points
a student pushes a hollow ball with a small amount of force causing it to roll quickly
across the room. the student then pushes a solid ball with the same amount of force.
which statement demonstrates an understanding of force and its effects on an object?
the force on both balls was the same; therefore each ball pushes back with
the same amount of force.
the force on both balls was the same; however each ball pushes back with a
different amount of force.
the solid ball pushes back with a greater force than the hollow ball, because
the solid ball has a greater mass.
the hollow ball pushes back with a greater force than the solid ball, because
the solid ball moved faster and further.

3 multiple choice 2 points
jeannie put her soccer ball on the ground on the side of a hill. which force acted on
the soccer ball to make it roll down the hill?
gravity
electricity
friction
magnetism

Explanation:

1.

When a man is standing on a chair, according to Newton's third law (action - reaction), the chair must exert an upward force equal to the man's weight (which is a force due to gravity acting on him) to keep him in equilibrium (not accelerating). If the man's weight is 800 newtons, the chair's supporting force must also be 800 newtons.

According to Newton's third law, for every action, there is an equal and opposite reaction. When a force is applied on an object (pushing the ball), the object pushes back with an equal force. The mass of the ball affects its acceleration (from Newton's second law \(F = ma\)), but the reaction force (ball pushing back) is equal in magnitude to the applied force for both balls since the applied force is the same.

Gravity is the force that acts on objects with mass, pulling them towards the center of the Earth. On a hill, the component of the gravitational force along the slope of the hill causes the soccer ball to roll down. Electricity, friction (which would oppose the motion in some cases, but not cause the ball to roll down the hill as the main force here), and magnetism (assuming no magnetic materials involved) are not the forces that make the ball roll down the hill in this common - sense scenario.

Answer:

800 newtons

2.