Newton’s Laws And Their Applications Flashcards
Weight
(Fg) the gravitational force the Earth exerts on any object on or near its surface.
Mass
(m) the amount of matter in an object (kg).
Normal force
the perpendicular force exerted by a surface on an object in contact with it.
Frictional force
the force that opposes the motion of an object and acts parallel to the surface with which the object is in contact with.
Static friction
frictional force keeping object at rest.
Kinetic friction
force acting in the opposite direction to motion
Kinetic friction vs Static friction
- fk < fs(max)
- less force required to keep an object sliding at constant velocity than to start it sliding
- μk < μs
- for a pair of objects fk can have only one value; for same 2 objects fs can have any value up to a maximum of fs(max)
Newton’s first law
an object continues in a state of rest or uniform (moving with constant) velocity unless it is acted upon by a net or resultant force.
A body moving with constant velocity
- is in equilibrium
- has no net force acting on it
Inertia
the property of an object that causes it to resist a change in its state of rest or uniform motion.
Newton’s second law
when a net force, Fnet, is applied to an object of mass, m, it accelerates in the direction of the net force. The acceleration, a, is directly proportional to the net force and inversely proportional to the mass.
Actual weight vs Apparent weight
- Actual weight = weight (Fg)
- Apparent weight = contact force on object (usually N)
- if N ≠ Fg the apparent weight ≠ actual weight
- if Fnet upwards, N > Fg
- if Fnet downwards, N < Fg
Tension
a pulling force that acts away from object.
Compression
a pushing force that acts towards the object.
On inclined plane
- Components of weight (perpendicular and parallel)
- Normal force
Perpendicular component of weight - Fg⊥ = Fg cosΘ
Parallel component of weight - Fg|| = Fg sinΘ
Normal force - N = -Fg⊥
