**Newton's Third Law**

For every action there is an equal and opposite reaction. A force is either a push of a pull to cause motion to an object. These two forces are called the

action

and

reaction

force. These to forces are always present in any interaction of two objects.

**Newton's Laws of Motion**

**Common Newton's Laws Misconceptions**

**Citation**

**Newton's First Law**

Newton's first law of motion states that an object will stay in motion and move at a constant velocity and an object at rest will stay at rest unless an unbalanced force acts on it.

**Newton's Second Law**

**Newton's Laws of Motion**

By: Brayton Larson, Hamming Lin, Brendan Moss

Hour: 1

Date: March 31, 2014

**In Summary**

**F = M*A**

The acceleration of an object is directly proportional to the net force acting on the object is and inversely proportional to the mass of the object.

In this example the first law of motion is shown through this classic "magic" trick as the wine glasses keeps its position as the chef pulls the table cloth. The trick works because objects have inertia, a tendency to stay at a constant velocity. In this case the objects are the wine bottles and the velocity is zero. Since the force applied from the chef's hand and tablecloth to the plate and wine bottles is not of a great amount and of a large amount of time the plate and wine bottles do not have enough time to accelerate before the force from the table cloth is gone and friction takes over as the dominate force and stops the objects from moving.

In this example though the exact opposite is happening which is described by the same law. As it describes, the law states that an object will remain in motion until an unbalanced force acts upon it. In this case the object is the crash dummy and the unbalanced force is the front dashboard. Since the dummy isn't constrained to the car, the dummy shoots forward and smashes into the dashboard. The sudden negative acceleration, when hitting the dashboard because of the lack of an airbag, would have caused tremendous injuries. With the seat belt and airbag however, the dummy decelerates at a much smaller scale decreasing the chance for injury.

**By: Derek**

at Veritasium

at Veritasium

This example shows how the mass of an object effects how far it will travel. Two balls, one with less mass than the other, are placed in an air cannon and fired across the room with the same amount of force. The test clearly shows the object with less mass travels with a greater acceleration than the one with more mass.

Newton's second Law tells us that Force required to move an object is equal to the amount of mass of the object multiplied by acceleration desired (F=M · A). As long as we have at least two of any of these variables we can calculate the third. For instance if we need force applied and we have both mass and acceleration all we have to do is multiply the two together and we are done. Examples below to clarify.

Example 1

Calculating

Here we see a ping pong ball being hit by a

paddle. In this example the force is represented by what is exerted by the paddle, the mass is that of the ping pong ball, and the acceleration is of the ball after being hit. Let's break it down a little more.

As shown in the picture above, force is represented by the green arrow, acceleration by the red, and mass by the blue. Out of the three the only variable unknown is force. To find this we have to use our formula (F=M · A).

force: ?

mass: 2.3 g

acceleration: 10 m/s^2

mass: 2.3 g

acceleration: 10 m/s^2

force: ?

F=M · A

Force = 23 N

F= 2.3(10)

Start with our formula.

Plug in everything we know.

F= 23

Solve.

As seen in this short clip, the swimmers push against the wall of the swimming pool creating a force in the opposite direction launching the swimmers forward. The

action

force are the legs a swimmer pushing the wall. In contrast, the equal but opposite

reaction

force is the wall propelling the swimmer in the opposite direction.

Add units.

Afterward, there is another force provided by the swimmer: her body waves under water. As she uses her legs and feet to push the water back, an equal but opposite force is pushing her forward. This is another case of action and reaction forces.

**Here we can see an example of all three law of motion in action.**

**Since the plane is at rest, it will stay at rest on the tarmac until an unbalanced force acts on it**

(First law of motion)

. This unbalanced force are provided by the Rolls-Royce Trent 1000 engines which each provide at max 63600 lb (280 kN). Together they provide an astounding 565,814 Newtons of force. If the plane has an approximate mass of 18000 kg we can solve for it's acceleration

(Second Law of Motion)

. Lastly the engines provide force thrust backwards (action force) while an equal but opposite force launches the plane forward

(Third Law of Motion)

.

(First law of motion)

. This unbalanced force are provided by the Rolls-Royce Trent 1000 engines which each provide at max 63600 lb (280 kN). Together they provide an astounding 565,814 Newtons of force. If the plane has an approximate mass of 18000 kg we can solve for it's acceleration

(Second Law of Motion)

. Lastly the engines provide force thrust backwards (action force) while an equal but opposite force launches the plane forward

(Third Law of Motion)

.

force

acceleration

mass

A = F/M

Start with our formula

.

A = 565814N/18000kg

Plug in everything we know.

A = 31.43

Solve.

A = 31.43 m/s^2

Add units.

In this short clip, we see a baseball player at the mound. As he winds up to swing, a 70 mph fastball comes speeding towards his bat. When the two make contact both exert an equal but opposite force on the other. If we consider the bat's force on the ball launching it in the air as the action force, we must call the balls force on the bat as the reaction force; this also works vice-versa. The reaction force of the ball is great enough to break the batter's bat!

Example 2

In this iconic video taken during the Apollo 15 mission, two objects are dropped and they fall at the same rate. Of course the hammer has more mass than the feather yet they fall at the same rate. The feather here is a falcon feather which has an approximate mass of 0.03 kg the hammer has a mass of 1.32 kg. We also know the acceleration due to gravity on the moon is 1.624 m/s^2. With this information we can figure out the force pulling on both objects.

Feather

mass: .03 kg

acceleration: 1.624

force:

?

Hammer

mass: 1.32 kg

acceleration: 1.624

force:

?

Falcon Feather

Hammer

Gravity

(Force)

Acceleration

Mass

As shown in the picture below we can see that the hammer and feather are both accelerating at the same rate towards the ground. We are missing Force but we have both mass and acceleration we can calculate it with our formula:

F=M · A

Force:

?

mass(hammer):

1.32 kg

mass(feather):

.03 kg

acceleration: 1.624 m/s^2

F=M · A

Force = 2.14368 N

F= 1.32(1.624)

Start with our formula.

Plug in everything we know.

F= 2.14368 N

Solve.

Add units.

F=M · A

Force = .04872 N

F= .03(1.624)

Start with our formula.

Plug in everything we know.

F= .04872 N

Solve.

Add units.

Hammer

Feather

**Air/Water Powered Rocket**

When designing our vehicle we decided to go with a rocket, except instead of shooting upwards it flies horizontally. We considered several ways of propelling it and determined pressurized air would work best. For the body of our rocket we used a 16 oz plastic soda bottle which also served as a "pressure tank" for the air. In order to stabilize the rocket during flight we added fins, this helped but it still wasn't aerodynamic enough. For the final improvement we added a nose cone.

"Acceleration of Gravity." Acceleration of Gravity. The Physics Classroom, n.d. Web. 28 Mar. 2014.

"Crash Test with and without Safety Belt." YouTube. YouTube, 28 May 2009. Web. 30 Mar. 2014.

Cronin, Cam. "Newton's Second Law of Motion." YouTube. YouTube, 17 Dec. 2009. Web. 30 Mar. 2014.

"DeMarini Bat Breaking." YouTube. YouTube, 18 Apr. 2010. Web. 30 Mar. 2014.

"Feather & Hammer Drop on Moon." YouTube. YouTube, 05 July 2006. Web. 30 Mar. 2014.

"Magic Table Cloth Trick." YouTube. YouTube, 12 Mar. 2010. Web. 30 Mar. 2014.

"Missy Franklin Slow Motion Start - W 200 Backstroke - ARENA Grand Prix Series at Santa Clara." YouTube. YouTube, 01 June 2013. Web. 30 Mar. 2014.

"Osnovna škola Prečko Zagreb." Daliborka Pavić. Osnovna škola Prečko Zagreb, n.d. Web. 30 Mar. 2014.

Three Incorrect Laws of Motion. Prod. Derek. Perf. Derek. YouTube. Veritasium, 10 Mar. 2011. Web. 20 Mar. 2014.

Williams, David R. "The Apollo 15 Hammer-Feather Drop." Apollo 15 Hammer-Feather Drop. NASA, 12 Feb. 2008. Web. 30 Mar. 2014.

Yes, that is indeed the rocket!

Action Force

Reaction Force

Air Drag (friction)

Gravity

Our Modifications:

Nose Cone

Stabilizing Fins

Effects of modification:

The nose cone increases the aerodynamics of the rocket, reducing drag and increasing the net force applied to the rocket

The stabilizing fins increase the amount of drag near the tail of the rocket so that it will say straight. The tail fins work by increasing the drag when the rocket is moved by an external force (e.g. the wind). These fins work because it creates a direction of travel for the rocket that has the least amount of drag. This is the same idea that allows a weather vane to work.