Exam 2 Flashcards
Newtons 3 Laws
- Natural state of motion
- sum of F = ma
- action forces are equal and opposite to reactive forces
Four field forces
strong (nuclear)
Electromagnetic
Weak (nuclear)
Gravity
Newton’s First Law
object moves with a velocity that is constant in magnitude and direction unless acted on by a non cero force
What is a consequence of the first law?
feasibility of space travel
Newton’s second Law
acceleration of an object is directly proportional to the net force acting on it and inversely proportional to mass
SI unit of force
Newton
1 N= 1(kg m)/s^2
Newton’s second law provides an explanation for
the equal accelerations of free falling objects with different masses
Free fall- the greater the mass…
greater its force attraction to earth is
the greater its inertia
Newton’s third Law
If two objects interact, the force exerted by object 1 on object 2 is equal in magnitude but opposite in direction to the force exerted by object 2 on object 1
Isolated force CANNOT exist
equilibrium
an object is either at rest or moving with a constant velocity
net force= 0
In Free body diagram what is positive?
right/up
in a free body diagram what is negative?
left/down
Friction is proportional to…
normal force
friction is independent of…
area of contact
velocity
Direction of friction is
opposite the direction of motion
if F increases…
so does fs
If F decreases…
so does fs
What is the units for coefficient of friction?
TRICK
has no units
What is greater usually, fs or fk?
fs
what does a large k (spring constant) mean
stiff spring
what does a small k mean
soft spring
Why is k negative in Hooke’s law?
force is always directed opposite to displacement
What is the displacement at the equilibrium position?
0
where is centripetal acceleration directed?
towards the center
