Transcript Newton`s 2nd Law - Solon City Schools

General Physics
NEWTON’S
ND
2
LAW
Definition
 Fnet = ma
 m (kg)
2
 a (m/s )
 F Net (N= kg x m/s2)
Graph of F and a
 Directly related
a = kF
acceleration
Force
Graph of a and m
 Inversely related
Accel.
a=
mass
-1
km
Questions
 a = F/m
 If Fnet is doubled, acceleration is
doubled
 If mass is doubled, acceleration is
cut in half
Finding acceleration
 A holiday tree is being pulled
across a parking lot with a force of
20 N. If the tree is 25 kg and the
frictional force of the ground is 5
N, what is the acceleration of the
tree?
Finding Acceleration
 Free-body diagram
Fg = FN
Fric = 5 N
FApp =
20 N
 Fnet = m x a
 (20N – 5N) = 25 kg x a
 a = 0.6 m/s2
Weight
 Measure of force of gravity on
an object
 Equation: Fg (W) = mg
 Units: Newton
 1 N = 0.22 pounds
Review
 Which of the following describes an object
in equilibrium?
1. Uniform motion
2. Net Force = 0
3. Accelerating
4. Constant Velocity
5. Following Newton’s First Law
Review
 What is Newton’s First Law?
 What is Newton’s Second Law?
 What is Fnet?
 What does it mean if Fnet = 0
 What is another name for Fg?
 How are Mass and Weight related?
 What is the Normal Force of an object with a
mass of 5 kg that sits on the floor?