Today is Tuesday 1/23Learning Target: I can describe Newton’s 2nd Law of Motion.

You will need:⊗ Pencil⊗ Science notebook⊗ Warmup

Have your notebook out to yesterday’s homework and stations

for a stamp (1 for your homework and 1 for the stations being completed

and glued in).

Newton’s 2nd Law: Describes the relationship between Force, Mass, and Acceleration.The acceleration of an object by force is inversely proportional to the mass of the object, and directly proportional to the force.

Let’s break it down:

Part 1 : (1)The acceleration of an object by force is inversely proportional to the mass of the object, and (2)directly proportional to the force.

⊗ (1)Acceleration and mass inversely proportional (when one goes up the other goes down): When force is constant, the smaller the mass, the more it will accelerate. The larger the mass, the less it will accelerate.

⊚ Ex: If you apply the same amount of force to 2 objects, a marble and a bowling ball, which one will accelerate more? (the marble, because it has less mass)

Part 2 : (1)The acceleration of an object by force is inversely proportional to the mass of the object, and (2)directly proportional to the force.

⊗ (2)Acceleration and Force are directly proportional (when one goes up so does the other): The greater the force applied to something, the more the object will accelerate.

⊚ Ex: Think of a swingset, when somebody is pushing you on a swing set with a small amount of force you swing slowly, but when a strong person pushes you with a lot of force you swing a lot faster.

Recap: What does Newton’s 2nd Law say?

⊗ The more mass something has the less it will accelerate. (Mass and acceleration are inversely related)

⊗ The more force is applied to an object the more it will accelerate. (Force and acceleration are directly related)

Force and Mass affect acceleration.

Re-write Newton’s 2nd law in your own words

The relationship between Force, Mass, and Acceleration can be shown with the following formula:

F = m x a(Force = mass x acceleration)⊗ The force of an object comes from its mass and acceleration.⊗ Force is measured in Newtons (N)

2nd Law Formula : F = m x a⊗ Something very massive (high mass) that’s

changing speed very slowly (low acceleration), like a glacier, can still have great force.

⊗ Something very small (low mass) that’s changing speed very quickly (high acceleration), like a bullet, can still have a great force. Something very small changing speed very slowly will have a very weak force.

Using the 2nd Law FormulaMike's car, which weighs 1,000 kg, is out of gas. Mike is trying to push the car to a gas station, and he makes the car go 0.5 m/s². Using Newton's Second Law, you can calculate how much force Mike is applying to the car. • F = m x a

• F= 1000 kg x .5 m/s2

• F= 500 k x m/s2

• F= 500 N

Try it!

What force is needed to push a 10kg shopping cart at 3 m/s² ?

• F=m x a• F= 10 kg x 3 m/s2

• F= 30 N

Just like with the speed formula, you can rearrange the 2nd law formula to find any of the variables.

F = m x aM = F/aA = F/m

http://www.classzone.com/books/ml_science_comp/page_build.cfm?id=none&mod=13##

Question

• Identical twins are riding in identical wagons. A friend gives the first wagon a stronger push than the second. Which twin will experience greater acceleration?

Question•Would a car towing a boat take less, the same, or more time to accelerate than it would without the boat? Explain.

Question

•What will happen to the acceleration of an object if the mass decreases and the force is constant?

Question• If two identical objects accelerate at the same rate, what must be true of the force applied to each object?

Homework:Newton’s 2nd Law Worksheet