P.Sci.-SPS8 - Unit 1 - Force & Motion -
Machine
A device that makes work easier by changing the size or direction of a force
Rolling Friction
A friction force that acts on rolling objects, caused by the change in shape at the point of contact
Static Friction
A friction force that acts upon objects that are not moving
Sliding Friction
A friction force that opposes the motion of an object as it slides over a surface
Fluid friction
A friction force that opposes the motion of an object through a fluid
Force
A push or pull that acts upon an object
Pulley
A simple machine that consists of a rope that fits into a groove in a wheel
Inclined plane
A simple machine that is a flat, sloped surface - ex. ramp
Wedge
A simple machine that is an inclined plane that moves- ex. axe
Frame of reference
A system of objects that are not moving with respect to one another
Screw
An inclined plane wrapped around a cylinder
Air Resistance
Fluid friction acting on an object moving through the air
Distance
How far an object has moved
Law of conservation of momentum
Law stating that the total momentum of a system does not change if no net force acts on the system
Mechanical Advantage
Ratio of the output force exerted by a machine to the input force applied to the machine (number of times the machine increases the output force)
Watt
SI unit of power equal to one joule of work per second.
Joule
SI unit of work equal to one newton-meter
Wheel and axle
Simple machine made from two different-sized, circular objects that are connected and rotate together
Mass
The amount of matter in an object
Gravity
The attraction between two objects because of their masses
Terminal Velocity
The constant velocity of an object falling when the force of air resistance equals the force of Gravity
Projectile Motion
The curved path of an object in free fall after it is given an initial foreword velocity
Speed
The distance an object travels per unit of time
Output distance
The distance an output force acts through in a machine
Input distance
The distance through which the input force acts in a machine
Fulcrum
The fixed point around which a lever pivots
Output force
The force exerted on an object by a machine
Weight
The force of gravity acting upon an object
Friction
The force that opposes the motion of objects that touch as they move past each other
Input force
The force you exert on a machine
Free fall
The motion of a falling object when the only force acting on it is gravity
Net Force
The overall force acting upon an object after all of the forces are combined
Efficiency
The percentage of the input work that is converted to output work
Momentum
The product of an object's mass and it's velocity
Work
The product of force and distance (motion must be in same direction as force)
Acceleration
The rate of change of velocity
Newton (N)
The si unit of force, equal to the force that causes a 1-kilogram mass to accelerate at a rate of 1 meter per second squared ( 1 kg x m/s^2)
Velocity
The speed and direction of a moving object
Instantaneous speed
The speed of an object at one instant of time
Inertia
The tendency of an object to resist change in it's motion
Average speed
The total distance traveled divided by the time it takes to travel that distance
Work output
The work done by a machine as the output force acts through the output distance
Work input
The work done by the input force acting through the input distance
compound machine
a combination of two or more simple machines that operate together
Lever
a simple machine that consists of a rigid bar that pivots at a fixed point called a fulcrum
Power
the rate at which work is done. P = W/t
