Day 1 - Do Now

• Take 1 minute to answer the question:

– Why would we want to measure force? (i.e. under what circumstances is measuring force useful?)

– Please write an example.

Sir Isaac Newton

Newton’s 2nd Law

• Newton’s 2nd Law gives us the ability to calculate how much force is required to move an object

The formula

• F = m X a(force = mass times acceleration)

F = ma

Playing with the formula

F F• F= ma OR m= -------- OR a= --------- a m • Units: unit for force is N (Newton)

m = kga = m/sec2

Newton = Kg xm sec2

Formula TrickCover the symbol you are trying to find!

2nd Law Quick Practice

• A 100 Kg linebacker hits the running back while accelerating at 3 m/s2. What is the force the linebacker hits the running back? Answer in Newtons

Quick Practice

F = m x a

mass = 100 Kg accel. = 3 m/s2

F = 100 Kg x 3 m/s2

F = 300 Kg x m / s2

Day 2 - Do Now

• Please take two minutes to answer this question:

• What is the funniest or most fun race you have ever participated in or have seen?

Wagon Race

Scenario

• One Saturday morning you and your eleven friends decide to have a wagon race. Each wagon team has a total of four people, arranged in the following manner and shown below in the diagrams:

• Wagon 1 – 2 people pushing the wagon and 2 people sitting in the wagon

• Wagon 2 - 3 people pushing the wagon and 1 person sitting in the wagon

• Wagon 3 - 1 person pushing the wagon and 3 people sitting in the wagon

WAGON #1

Force of Each Person Pushing the WagonPerson number Force (N)1 532 55

WAGON #1

Mass of Each Person in the Wagon

Person number Mass (Kg)3 314 37

WAGON #2

Force of Each Person Pushing the Wagon

Person number Force (N)5 556 317 11

WAGON #2

Mass of Each Person in the Wagon

Person number Mass (Kg)8 40

Force of Each Person Pushing the Wagon

Person number Force (N)9 80

WAGON #3

WAGON #3

Mass of Each Person in the WagonPerson number Mass (Kg)10 3711 5612 29

The following formulae may be used in this task:

F = ma

d = ½ at2

v=at

Units

Symbol UnitDistance d m (meter)

Mass m kg (kilogram)

Velocity v m/sAcceleration a m/s2

Time s s (second)

Force (Newton) N kg . m/s2

Step 1

1. Using the information contained in the prompt, calculate the acceleration of each wagon. Show all work and be sure to include all units in your calculations and answers.

The Accelerations

F=ma

ΣF=(Σm)a

Ex. F1+F2=(m1+m2)a

Σ = Summation or Sum Of or Total Of

Force on Wagon #1

Force of Each Person Pushing the WagonPerson number Force (N)1 532 55

ΣF= F1+F2 = 53N+55N = 108N

Mass of Wagon #1

Mass of Each Person in the Wagon

Person number Mass (kg)3 314 37

Σm= m3+m4 = 31kg+37kg = 68kg

Acceleration of Wagon #1

Force on Wagon #2

Force of Each Person Pushing the Wagon

Person number Force (N)5 556 317 11

ΣF= F5+F6+F7 = 55N+31N+11N = 97N

Mass of Wagon #2

Mass of Each Person in the Wagon

Person number Mass (Kg)8 40

Σm= m8 = 40kg

Acceleration of Wagon #2

Force of Wagon #3

Force of Each Person Pushing the Wagon

Person number Force (N)9 80

Σm= m9 = 80kg

Mass on Wagon #3

Mass of Each Person in the Wagon

Person number Mass (Kg)10 2711 4612 19

ΣF= F10+F11+F12 = 27N+46N+19N = 92N

Acceleration of Wagon #3

Day 3 - Do Now

• What kind of information can you calculate using the formula F=ma?

• How can you use these problems in real life?

Table Assumptions

2a. Assuming that each wagon maintains a constant acceleration for five seconds, construct a table which compares the speed and time of each wagon. Your table should represent every second from resting to five seconds.

TableTime (seconds) Speed (meters/seconds)

0

1

2

3

4

5

Using the Table

2b. Using the table you created, construct a single graph plotting the speed vs. time data for each of the three wagons.

GRAPHING

Calculating distance

• What is the distance travelled by each wagon?Wagon 1• d = ½ at2

• d = ½ (1.59 m/s2) 5 s 2

• d = ½ (1.59 m/s2) (25 s2)• d= ½ (39.75)• d= 19.88

The race!

• If a 200 meter race was held, which wagon would win?

• First of all how long is 200 meters? Bolt!• Use words to describe your thinking and

relate it to Newton’s second law:– Acceleration, mass and force!!!