Newton’s
nd
2
Law
Thursday, 19 March 2020
Newton’s
nd
2
Law: Starter
On the Starter WS, determine the Resultant Force and Direction in each case.
(02:06:55) 4 minutes
Answers.
A. 6 N
Right
B. 0 N
C. 5 N
Left
D. 10 N
Left
E. 10 N
Right
F. 0 N
G. 7 N
Left
H. 100 N
Right
Newton’s
nd
2
Law: Lesson Objectives
Understand and apply Newton’s 2nd Law of motion.
Newton’s
nd
2
Law: Learning Outcomes
1. Be able to determine which of Newton’s laws to apply
(balanced vs unbalanced forces).
2. Be able to restate Newton’s 2nd law and how force, mass and
acceleration are related.
3. Be able to apply Newton’s 2nd law.
Balanced Forces: Newton’s
st
1 Law
Recall Newton’s 1st Law
An object at rest stays at rest and an object in motion stays in motion
with the same speed and in the same direction unless acted upon by an
unbalanced force.
The first law will apply when the forces are balanced
From the starter WS determine where Newton’s 1st Law applies
(02:06:55) 1 minute
B and F
Newton’s
nd
2
Law: Resultant Force
The second law states that the acceleration of an object depends on
the Resultant Force acting upon the object and the Mass of the object.
Newton’s 2nd Law applies to Unbalanced Forces (when there is a
Resultant Force).
From the Starter WS determine where Newton’s 2nd Law applies
(02:06:55) 2 minutes
A
C
D
E
G
H
Newton’s
nd
2
Law: Equation
Acceleration = Force ÷ Mass
Example: Force = 30 N, Mass = 10 kg
Acceleration = 30 N ÷ 10 kg = 3 m/s²
From the Starter WS calculate the acceleration in each case (02:06:55)
6 mins
Force = Mass X Acceleration
Mass =
Force ÷ Acceleration
Units: mass – kg
(kilograms)
F – Newtons (N)
Acceleration – m/s²
(meters per second squared)
4N
10N
Resultant Force = 6 N
Calculate acceleration = F/m
15N
25N
Resultant Force = 10 N
Calculate acceleration = F/m
a = 10 N/2 kg = 5m/s²
5N
Resultant Force = 0 N
Calculate acceleration = F/m
a = 0 N/1 kg = 0 m/s²
5N
Resultant Force = 7 N
Calculate acceleration = F/m
a = 7 N/14 kg = 0.5 m/s²
500 N
Resultant Force = 100 N
Calculate acceleration = F/m
a = 100 N/50 kg = 2 m/s²
a = 6 N/6 kg = 1 m/s²
Mass = 6 kg
10N
Mass = 2 kg
10N
Resultant Force = 0 N
Calculate acceleration = F/m
5N
a = 0 N/10 kg = 0 m/s²
Mass = 10 kg
10N
Mass = 1 kg
5N
Resultant Force = 5 N
Calculate acceleration = F/m
12N
a = 5 N/2.5 kg = 2 m/s²
Mass = 2.5 kg
15N
Mass = 5 kg
Mass = 14 kg
5N
Resultant Force = 10 N
Calculate acceleration = F/m
a = 10 N/ 5 kg = 2 m/s²
400 N
Mass = 50 kg
Newton’s
nd
2
Law: Word Problems
(02:06:55) 5 mins
5 minutes
End
Newton’s
1st Law
st
1
and
nd
2
Laws Summary
2nd Law
A
Resultant Force =
4N
E
10N
15N
25N
Direction
Mass = 6 kg
Direction
Mass = 2 kg
B
Resultant Force =
10N
F
Resultant Force =
5N
10N
5N
Direction
Mass = 10 kg
C
10N
Direction
Mass = 1 kg
5N
Resultant Force =
G
Resultant Force =
12N
5N
Direction
Mass = 2.5 kg
Direction
Mass = 14 kg
D
Resultant Force =
15N
5N
H
Resultant Force =
400 N
Direction
Mass = 5 kg
Resultant Force =
500 N
Direction
Mass = 50 kg
Resultant Force = 6 N Right
4N
10N
Mass = 6 kg
15N
25N
Mass = 2 kg
Resultant Force = 0 N
10N
Resultant Force = 0 N
5N
10N
Mass = 10 kg
10N
5N
Mass = 1 kg
5N
Resultant Force = 5 N Left
Resultant Force = 7 N Left
12N
Mass = 2.5 kg
5N
Mass = 14 kg
Resultant Force = 10 N Left
15N
Mass = 5 kg
Resultant Force = 10 N Right
5N
Resultant Force = 100 N Right
400 N
Mass = 50 kg
500 N
A.
Resultant Force = 6 N
E.
Mass = 6 kg
Newton’s Law: 2ND
Mass = 2 kg
Newton’s Law: 2ND
B.
Resultant Force = 0 N
F.
Resultant Force = 0 N
4N
10N
10N
15N
5N
10N
25N
Resultant Force = 10 N
5N
Mass = 10 kg
Newton’s Law: 1ST
Mass = 1 kg
Newton’s Law: 1ST
C.
Resultant Force = 5 N
G.
Resultant Force = 7 N
10N
5N
12N
5N
Mass = 2.5 kg
Newton’s Law: 2ND
Mass = 14 kg
Newton’s Law: 2ND
D.
Resultant Force = 10 N
H.
Resultant Force = 100 N
15N
5N
400 N
Newton’s Law: 2ND
Mass = 5 kg
500 N
Newton’s Law: 2ND
Mass = 50 kg