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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!!!
