Forces and Motion
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What does inertia mean?
Reluctance to change Inertia is a property of matter that describes the tendency of an object to resist changes in its state of motion.
Why is the first law of motion called the law of inertia?
The first law says that whatever an object is doing, it wants to keep doing; in other words, it’s reluctant to change.
State the first law of motion.
Objects in motion stay in motion with the same velocity unless acted on by an unbalanced force. Objects at rest stay at rest unless acted on by an unbalanced force.
What happens when an object is acted on by a balanced force?
Nothing!
What does an unbalanced force cause?
An object to accelerate.
State the second law of motion.
An unbalanced force causes acceleration.
What equation is associated with the second law?
F=ma.
What does action at a distance mean?
A push or pull happens without coming in contact with the object.
What are the three action at a distance forces?
• Gravitational force • Electrical force • Magnetic force
What is the difference between mass and weight?
Mass is the measure of an object’s inertia, weight is the expression of gravity on an object’s mass.
What force creates weight?
Gravitational force.
What is the statement of the third law of motion?
For every action there is an equal and opposite reaction.
Is the reaction consecutive to the action or simultaneous with it?
Simultaneous.
Metrc symbols
wt and force - N g and a - m/s (for g its 10) m - kg p - kg*m/s
Imperial symbols
wt and force - lbs g and a - ft/s (for g its 32) m - slugs
F=???
ma
p=???
mv
wt=???
mg
Definition of Gravity
attract any mass to the center of the earth
Definition of Mass
the measure of an object’s inertia
Definition of Weight
the expression of gravity on an object’s mass