Who is doing this work?

What is the simplest definition of a force?

• A form of motion

• A push or a pull involving two or more objects

• A kind of magnetic attraction

• A type of energy

What unit is used to measure force?

• Newtons

• Joules

• Kilograms

• Meters per second squared

What does it mean when forces are balanced?

• The object is accelerating

• The forces are invisible

• The object is moving at constant speed

• The net force is zero

Which force is responsible for keeping a plane in motion?

• Engine thrust

• Magnetism

• Friction

• Gravity

What is drag?

• The force that pulls objects downwards

• The resistance of surface against motion

• The friction of air molecules against an object

• A push that moves objects forward

What kind of force is gravity?

• A visible force

• A balanced force

• A non-contact force

• A contact force

How does gravity act on objects?

• Through direct contact

• By reducing friction

• Through a field

• By increasing their mass

What happens when drag and gravity balance out during free fall?

• The object stops moving

• The object accelerates indefinitely

• The object's velocity becomes steady

• The object reverses direction

What effect does pulling the parachute cord have?

• Increases gravity

• Increases drag

• Both increases drag and decreases velocity

• Decreases velocity