Types of Friction
What is kinetic friction?
Kinetic friction is friction between moving surfaces.
The measure of the gravitational force on an object is its ______.
weight
What Italian scientist argued that the mass of an object does not affect the time it takes to fall to the ground?
Galileo Galilei
The curved path that an object follows when thrown, launched, of otherwise projected near the surface of Earth is called __________ ______.
projectile motion
When gravity is the only force acting on an object, the object is in ____ ____.
free fall
What are two types of kinetic friction?
Sliding and rolling
A measure of the amount of matter in an object is ____.
mass
Why is a heavier object harder to accelerate than a lighter object?
It has more mass
Motion perpendicular to the ground is called ________ ______.
vertical motion
The velocity at which a falling object travels when the force of air resistance exactly matches the downward force of gravity is called the ________ ________.
terminal velocity
What is static friction?
Static friction is when a force is applied to an object but does not cause the object to move.
What is the SI unit of force?
Newtons
The rate at which velocity changes over time is ____________.
acceleration
The unbalanced force that causes an object to move in a circular path is called a ___________ force.
centripetal
Which type of kinetic friction is usually greater, sliding, or rolling friction?
Sliding friction
What is the main SI unit of mass?
kilogram
On what two factors does acceleration depend?
force and mass
Everything on Earth is pulled downward toward the center by _______.
gravity
_______ is the tendency of an object to resist any change in its motion.
Inertia
As soon as a object starts moving, what replaces static friction?
Kinetic friction.
Besides the kilogram, what are two units often used to measure mass?
grams and milligrams
At what rate do all objects accelerate toward Earth?
9.8 meters per second per second
Motion parallel to the ground is called __________ ______.
horizontal motion
The fluid friction that opposes the motion of objects through air is know as ___ __________.
air resistance