Mechanics Flashcards
Newton’s first law
an object in motion will remain in motion unless acted upon by an unbalanced force
Newton’s second law
force=mass x acceleratoin
Newton’s third law
when one object exerts a force on a second object, the second object exerts an equal force in the opposite direction of the first object
ex; a canon moving backwards after shotting a bomb
Inertla
the tendency of an object to resist a change in motion
ex; a passenger will launch forward if a car suddenly stops suddenly
What’s weight
the gravitational force experienced by an object
Formula of weight
Fg=mg
g=(9.8)
Whats apparent weight
the force exerted by the scale
How does going up or down an elevator affect apparent weight
accelerating upwards:
feel heavier, scale reads less
accelerating downwards:
feel lighter, scale reads more
what’s drag force
the force exerted by a fluid on an object opposing motion through a fluid
what’s terminal velocity
the constant velocity that’s reached when the drag force equals the force of gravity Fg=Fd
what’s normal force
the prepindicular contact force that a surface exerts on another surface
what’s the resultant of two equivalent vectors in opposite directions
the resultant is zero
Formula for resultant of two prepindicular vectors
R^2=A^2+B^2
Formula for resultant of two prepindicular vectors with an angle between them
R^2=A^2+B^2-2ABcosthta
what’s friction force and its two types
opposing force between two surfaces in contact
1.kinetic
2.static
what’s Kinetic Fricition and its formula
Friction between moving surfaces:
Fk=microkxFn
microk=coofficient of kinetic force
Fn=normal force
what’s static friction
friction between unmoving objects
Characterstics of friction force
- does NOT depend on the surface area
- if thre is no force acting on the body, the static friction is zero
- there is neglible amounts of friction on smooth surfaces
Why is static friction represented by an inequality? (<=)
Because it is not a fixed number, it can be a range of numbers up to a maximum point
What’s the Fn normal force on an inclined plane
Fn=mgxcostheta
what are x and y on an inclined plane
x = mg x cos theta
y = mg x sintheta
does the mass affect the laws or calculations of free-fall?
no, because mass (m) does not play a role n any of the gravitational acceleration formulas
what is the difference between the formulas for kinetic acceleration and gravitational acceleration?
we replace every (a) with (g) which equal 9.8m/s^2
does a person’s mass change on the moon?
no, the mass of an object is conserved and constant.
the person’s weight is idfferent thoguh, because weight=mg
