Newton’s Second Law of Motion Take notes on page 47 of your notebook

Newton’s first law tells us that this soccer ball will remain at rest until a force acts on it. Newton’s second law tells us that force causes acceleration The acceleration also depends on mass.

Newton’s first law tells us that this soccer ball will remain in motion until acted on by a force. Newton’s second law tells us that the force of the man’s face caused the ball to accelerate. (acceleration is a change in speed or direction.) It also tells us that the acceleration depends on the mass of the ball. (mass is the amount of matter)

Answer on page 46 What must this little boy do to break the same board as a large man? (Hint: F = m x a )

Let’s say it with math! Force equals mass times acceleration F=ma Newtons = kilograms x meters per second squared Example: 500N = 100 kg x 5 m/s2

Solve this problem Write on page 46 of your notebook 2. A company uses a ramp to slide a box of parts to a shipping area. Each box weighs 10 kilograms. When sliding down the ramp, the box accelerates at a speed of 0.1 m/sec2. What is the force acting on the box?

Mass vs Weight Mass is the amount of matter in an object The mass of something remains the same on the earth, the moon, or even in the weightless vacuum of space Weight is a force created by gravity The weight of an object depends on the gravity of the planet and the mass of the object.

Mass vs weight Mass is measured in grams or kilograms (or micrograms, or picograms, or femtograms…anything with grams!) Weight is measured in Newtons, because it is a force.

Answer these questions Answer on page 46 of your notebook An astronaut has a mass of 75 kg. 3. What is her mass on the moon? 4. What is her mass in space? 5. What is her weight on the earth? 6. What is her weight on the moon? 7. What is her weight in space? HINTS: The acceleration of the earth’s gravity is 9.8 m/s2 The acceleration of the moon’s gravity is 1.6 m/s2

Some types of forces Gravity Electromagnetic Nuclear forces Friction

Friction Frictional force Opposes motion Rolling friction Viscous friction Frictional force Opposes motion Friction occurs when two surfaces move against each other Sliding friction Air friction

Equilibrium When you add up all the forces on an object, you get a NET Force. When the net force is not zero, motion occurs When the net force is zero, no motion occurs. This is called equilibrium The force of gravity is equal to the force of the sliding friction between the man’s shoes and the rock and the force of the rock pushing up on the man. His forces are in equilibrium.

Last assignment! On page 46, make a Venn diagram of mass and weight.

Coming Events Newton’s Third Law of Motion & Momentum Fan Cart Gizmo (What’s Mass Got To Do With It?) Lab with the cars and ramps Make a Newton’s Laws powerpoint