Section 2.2 Force and mass determine acceleration.

Vocabulary ___________________________ states that the acceleration of an object increases with increased force and decreases with increased mass. Newton’s Second Law

So… Increasing Mass Decreases Acceleration! Which shopping cart will have more acceleration if the same force is applied to both carts? So… Increasing Mass Decreases Acceleration! small mass same size force large mass same size force greater acceleration smaller acceleration

So… Increasing Force Increases Acceleration! Which shopping cart will have more acceleration? So… Increasing Force Increases Acceleration! same mass same mass greater force smaller force greater acceleration smaller acceleration

The apple will accelerate more because it has less mass. An apple and a bowling ball are pushed with the same force. Which one will accelerate more? Why? The apple will accelerate more because it has less mass.

Calculating Force F = ma F = force m = mass a = acceleration

Calculating Force Class Example What force is needed to accelerate a 10 kg shopping cart 3 m/s2? F = m x a F = 10 kg x 3 m/s2 F = 30 N

Calculating Force Practice Problem #1 If a 5 kg ball is accelerating 1.2 m/s2, what is the force on it? F = 5 kg x 1.2 m/s2 F = 6 N

Calculating Force Practice Problem #2 A person on a scooter is accelerating 2 m/s2. If the person has a mass of 50 kg, how much force is acting on that person? F = 50 kg x 2 m/s2 F = 100 N

Calculating Acceleration What would the equation look like if I knew the force and the mass, but needed to find the acceleration?

Calculating Acceleration Class Example If a team pulls with a combined force of 9 000 N on an airplane with a mass of 30 000 kg, what is the acceleration of the airplane? a = 0.3 m/s2

Calculating Acceleration Practice Problem #1 Half the people on the team decide not to pull the airplane. The combined force of those left is 4 500 N, while the airplane’s mass is still 30 000 kg. What will be the acceleration? a = 0.15 m/s2

Calculating Acceleration Practice Problem #2 A girl pulls a wheeled backpack with a force of 3 N. If the back pack has a mass of 6 kg, what is its acceleration? a = 0.5 m/s2

Calculating Mass What would the equation look like if I knew the force and the acceleration, but needed to find the mass?

Calculating Mass Class Example A model rocket is accelerating at 2 m/s2. The force on it is 1 N. What is the mass of the rocket? m = 0.5 kg

Calculating Mass Practice Problem #1 Another model rocket is accelerating at a rate of 3 m/s2 with a force of 1 N. What is the mass of the rocket? m = 0.3 kg

Calculating Mass Practice Problem #2 A boy pushes a sign with a force of 10 N, and the sign accelerates 2 m/s2. What is the mass of the sign? m = 5 kg

Thinking Question It can simply change direction! How can an object accelerate when it does not change speed? It can simply change direction!

True or False? _____ A force can make an object change direction. _____ If an object only changes direction then it is not accelerating. _____ An object moves in the direction the force is applied. _____ Forces can cause acceleration. True False True True

Vocabulary Any force that keeps an object moving in a circle is known as _____________ force. centripetal

Where does the force point towards? If you let go of the string, the ball would fly off in the direction it was headed when you let go. This is called the path of inertia.

What do the blue arrows represent? centripetal force What do the black arrows represent? The path of inertia