Mechanical Comprehension on SIFT
Exam-Graded A
Inertia - ANSWER-An object's tendency to resist a change in motion
Force - ANSWER-A push or a pull
What is the unit of force? - ANSWER-Newton
Mass - ANSWER-A measure of how much matter is in an object
A measure of inertia of an object... An object with a larger mass will resist a change
more.
System - ANSWER-A collection of particles or objects that is isolated from its
surroundings.
All forces within a system are called internal forces, and forces outside the system are
called external forces.
Newton's first law - ANSWER-Law of Inertia
An object at rest stays at rest and an object in motion stays in motion with the same
speed and in the same direction unless acted upon by an unbalanced force.
Newton's second law - ANSWER-F=ma
Force equals mass times acceleration
An object in equilibrium - ANSWER-It is either at rest or moving at a constant speed.
No acceleration... a=0
Equilibrium condition - ANSWER-When a=0; therefore, F=0
Newton's third law - ANSWER-For every action there is an equal and opposite reaction
What are the four fundamental forces that form the basis for all other forces? -
ANSWER-1. Gravitational
2. Weak
3. Electromagnetic
4. Nuclear
, Gravitational force - ANSWER-The force that pulls mass together
Electromagnetic force - ANSWER-The force between electric charges. Repulsive when
the charges are the same sign and attractive when the charges are opposite.
Holds the positive nuclei and negative electrons of atoms together.
Nuclear (or strong) force - ANSWER-Holds together the nucleus in an atom.
The nuclear force has a larger magnitude than the electromagnetic force that pushes
protons (positive charges) away from each other in the nucleus.
Non-fundamental forces - ANSWER-Forces that can be derived from the four
fundamental forces.
Include weight, tension, friction, the normal force, and the buoyant force.
Weight - ANSWER-The gravitational force exerted on an object (Fw)
W=mg
Tension - ANSWER-Pressure; stress that occurs when forces act to stretch an object
(Ft or T)
Friction - ANSWER-The resistance that one surface or object encounters when moving
over another (Ff)
Normal force - ANSWER-Occurs when an object is resting on another object (Fn or N)
Always equal and opposite to the force pushing onto the surface
Applied force - ANSWER-A force which is applied to an object by a person or another
object (Fa)
Free-body diagram - ANSWER-A diagram showing all the forces acting on an object
Because all forces are vectors, it is important to consider the direction of the force when
drawing a diagram
What is the acceleration due to gravity? - ANSWER-g = 9.8 m/s^2
Always points to the center of the earth
What are the types of friction? - ANSWER-1. Static
2. Kinetic
Exam-Graded A
Inertia - ANSWER-An object's tendency to resist a change in motion
Force - ANSWER-A push or a pull
What is the unit of force? - ANSWER-Newton
Mass - ANSWER-A measure of how much matter is in an object
A measure of inertia of an object... An object with a larger mass will resist a change
more.
System - ANSWER-A collection of particles or objects that is isolated from its
surroundings.
All forces within a system are called internal forces, and forces outside the system are
called external forces.
Newton's first law - ANSWER-Law of Inertia
An object at rest stays at rest and an object in motion stays in motion with the same
speed and in the same direction unless acted upon by an unbalanced force.
Newton's second law - ANSWER-F=ma
Force equals mass times acceleration
An object in equilibrium - ANSWER-It is either at rest or moving at a constant speed.
No acceleration... a=0
Equilibrium condition - ANSWER-When a=0; therefore, F=0
Newton's third law - ANSWER-For every action there is an equal and opposite reaction
What are the four fundamental forces that form the basis for all other forces? -
ANSWER-1. Gravitational
2. Weak
3. Electromagnetic
4. Nuclear
, Gravitational force - ANSWER-The force that pulls mass together
Electromagnetic force - ANSWER-The force between electric charges. Repulsive when
the charges are the same sign and attractive when the charges are opposite.
Holds the positive nuclei and negative electrons of atoms together.
Nuclear (or strong) force - ANSWER-Holds together the nucleus in an atom.
The nuclear force has a larger magnitude than the electromagnetic force that pushes
protons (positive charges) away from each other in the nucleus.
Non-fundamental forces - ANSWER-Forces that can be derived from the four
fundamental forces.
Include weight, tension, friction, the normal force, and the buoyant force.
Weight - ANSWER-The gravitational force exerted on an object (Fw)
W=mg
Tension - ANSWER-Pressure; stress that occurs when forces act to stretch an object
(Ft or T)
Friction - ANSWER-The resistance that one surface or object encounters when moving
over another (Ff)
Normal force - ANSWER-Occurs when an object is resting on another object (Fn or N)
Always equal and opposite to the force pushing onto the surface
Applied force - ANSWER-A force which is applied to an object by a person or another
object (Fa)
Free-body diagram - ANSWER-A diagram showing all the forces acting on an object
Because all forces are vectors, it is important to consider the direction of the force when
drawing a diagram
What is the acceleration due to gravity? - ANSWER-g = 9.8 m/s^2
Always points to the center of the earth
What are the types of friction? - ANSWER-1. Static
2. Kinetic
