Transcript Newton`s Second Law 1 PPT

Objective
• SWBAT describe Newton’s second law of
motion and use it to explain the movement of
objects.
Chart of the Day
Review: Vocabulary
• Force: a push or a pull
• Net force: the sum of all forces acting on an
object.
• Balanced forces: forces that cancel each other
out  objects do not accelerate
• Unbalanced forces: forces that do not cancel
each other out  object accelerates
Review: Newton’s First Law of Motion
• An object at rest will remain at rest unless
acted upon by an outside force.
• An object in motion will remain moving at the
same speed unless acted upon by an outside
force.
How it relates to velocity-time
graphs…
Newton’s Second Law of Motion
• When a force acts on an object, the object
accelerates in the direction of the force.
net force (in Newtons)  mass (in kg)  acceleration (in m/s 2 )
Fnet  ma
Newton’s Second Law of Motion
(cont.)
Fnet ma

m
m
Fnet
a
m
Check For Understanding
• A box with a mass of 20 kg is pushed with an
acceleration of 2 m/s2. The force acting on the
box is…
A. 5 N
B. 10 N
C. 20 N
D. 40 N
Check For Understanding
• An object with a mass of 30 kg is moving at a
constant speed of 10 m/s. What force is
pushing the object?
– v = constant at 10 m/s  acceleration = 0 m/s2
– m = 30 kg
F  (30 kg)(0 m/s )  0 N
2
Check For Understanding
• What will be the acceleration of an 8kg object
when it is pushed with a force of 16 N?
A. 0.5 m/s2
B. 128 m/s2
C. 2 m/s2
D. 4 m/s2