Transcript Newton`s Laws

Newton’s 1st Law of
Motion
• Object in
motion
stays in
motion
Newton’s 1st Law of
Motion
• And
Objects
at rest
stay at
rest
Newton’s 1st Law of
Motion
• Until they are acted upon
by unbalanced forces.
Inertia or Newtons 1st Law
• Tendency for an
object to stay at
rest or moving in
a straight line at
a constant speed.
• The mass (m
measured in kg)
of an object
determines its
inertia
Newton’s 2nd
Law of Motion
Force = Mass X
Acceleration
F=ma
Weight (pull of gravity) is a
commonly measured force,
calculated by F=mg, g is the
acceleration due to gravity 9.8
m/s2
Newton’s 2nd Law of Motion
The greater the
mass of an
object, the
greater the force
required to
change its
motion.
Newton’s 2nd Law of Motion
• The greater the
acceleration of
an object, the
greater the
force required
to change its
motion.
11 The frog leaps from its resting position at the lake’s
bank onto a lily pad. If the frog has a mass of 0.5 kg and
the acceleration of the leap is 3 m/s2, what is the force the
frog exerts on the lake’s bank when leaping?
•
•
•
•
A 0.2 N
B 0.8 N
C 1.5 N
D 6.0 N
Formula chart says F=ma, m is mass in kg,
a is acceleration in m/s2.
So, .5 kg x 3 m/s2= 1.5 N
Newton’s 3rd Law of Motion
• For every
action force
there is an
equal and
opposite
reaction
force.
Newton’s 3rd Law of Motion
All forces come
in actionreaction pairs
Ex: feet push
backward on floor,
the floor pushes
forward on feet
27 A ball moving at 30 m/s has a
momentum of 15 kg·m/s. The mass of the
ball is —
A 45 kg
B 15 kg
C 2.0 kg
Formula Page says that
Momentum = Mass x Velocity
D 0.5 kg
So 15 kg.m/s = M x 30 m/s
solving for M it is: