Newtons 2nd LawForce on ObjectObjects acted on by a net
unbalanced force will accelerate in the direction of the forceThis
means they will speed up, slow down, or change directionNewtons 2nd
LawThe acceleration of an object is directly proportional to the
net force acting on it and inversely proportional to the mass. The
direction of acceleration is the same as the direction of the
forcea = F / m F = ma
Force RedefinedForce can be redefined as an action capable of
accelerating an objectUnit of force is the Newton (N)One Newton is
the force needed to accelerate a 1 kg mass at 1 m/s21 N = 1 kg
m/s2
ExamplesWhat force is needed to accelerate a 1000kg car at
g?
What is the net force required to bring a 1500 kg car to rest
from 100 km/hr within a distance of 55 m?A 50 kg go-cart starts
from rest and is accelerated by a 550 N force. If the cart
experiences a 280 N friction force and 35 N of air resistance,
finda) its accelerationb) its velocity after 3.0 sc) its
displacement after 3.0 sWhat force must be exerted on a 500 kg
crate in order to move it from rest to 3.0 m/s in 1.0 s?If we apply
Newtons 2nd Law to objects accelerating due to gravity
FG = mg
FG force of gravity, commonly called weight
W = mg2nd Law and GravityWhen an object is resting on the
surface of Earth, the force of gravity is still acting, even though
the object is not movingWhen the contact force acts perpendicular
to the surface it is referred to as the Normal Force (FN)NormalA
10.0kg box is resting on a tablea) draw the free body diagramb) now
it is pushed down with a force of 40N. Draw the free body
diagram.c) now it is pulled up with a force of 40N. Draw the free
body diagram.ExA 3.5kg box is resting on the floor. Draw the free
body diagramExampleWhat happens when the box in the previous
problem is pulled up with a force of 100N?Ex.
