Newton's Second Law of Motion

Additional information about weight

- A downward pull; a force - Can be zero - Affected by changes in gravity - Measured with a spring scale - Gravity's effect on mass

Gravity

- An attraction between two objects; the acceleration of an object towards another - A form of acceleration - Measured in m/s/s (or m/s^2)

Acceleration

- An increase in the velocity, or speed (+direction), of an object over time. - The rate at which an object's velocity changes over time - A change in velocity--the object's speed and direction (the measurement) - The result of a force being applied to an object that changes the object's velocity

FSSL

- Formula - Substitute - Solve - Label

Difference between weight and gravity

- Gravity is the attraction between two objects, or the acceleration of an object towards another. - Weight is the FORCE that an object exerts on another due to gravity

What did Galileo suspect about Aristotle's beliefs?

- He thought that not all of his universally accepted theory was true - He predicted that differences between how fast different types of objects fall has nothing to do with their mass

With a constant (same) mass, what happens to the acceleration of the object if the amount of force applied increases? What if force decreases?

- If the amount of force applied to an object increases, the acceleration also increases--as force and acceleration are directly proportional to each other. - If the amount of force applied decreases, so does the acceleration.

With a constant force, what happens to the acceleration if the mass of the object increases? What if the mass decreases?

- If the mass of the object increases, then the acceleration will decrease--or the object will decelerate. The object will travel at a slower rate. - If the mass decreases, the acceleration increases, as mass and acceleration are indirectly proportional to each other.

Why does a heavier object fall with the same acceleration as a lighter object?

- It takes more force to move a heavier object, as they have more inertia. - The ratio of force to inertia is the same for all objects. Thus, everything accelerates at the same rate and lands at the same time.

Additional information about mass

- Not affected by changes in gravity - Measured with a triple beam balance - Measured in grams

What did Aristotle believe?

- Objects of greater mass fall faster than those with less mass (turned out to be false) E.g: a piece of paper drifts to the ground far more slowly than a falling soccer ball

What did Galileo conclude?

- The effect of gravity on earthly objects is the same, regardless of the mass of those objects. - All falling objects accelerate toward Earth at the same rate - He realized that gravity existed, and Earth's gravity--otherwise known as its gravitational pull--that pulls on matter results in weight

Weight

- The force that an object exerts on another due to gravity; measured in Newtons (N) - The force of gravity on a body - Not the same as mass - Weight = (Mass)(Gravity)

Additional information about acceleration

- The greater the force, the greater the acceleration - The greater the mass, the greater the force needed for the same acceleration (E.g: when you push a chair and a sofa with the same force, the chair moves much faster because it has less mass and the sofa moves less because it has more mass) - Mass and acceleration are indirectly proportional to one another. So as mass increases acceleration decreases.

Examples of Newton's 2nd Law

- The harder you hit a baseball, the faster the ball moves (so the farther it travels over time) - Accelerating (speeding up) or decelerating (slowing down) a car depends on the mass of the car and how fast it is traveling - Positioning football players with the massive players on the line and the lighter players (of which are easier to accelerate) behind them - When riding a bicycle, you exert a force on the pedals, accelerating the bike. The harder you push, the faster the bicycle will move, thus traveling farther over time.

Work

- The result of a force that changes the motion of an object (overcomes inertia to stop or start its motion) - Done when a force that is applied to an object moves that object

How does inertia impact when you push or drop an object?

- To move an object with more mass, a larger force must be exerted to overcome its inertia--as the object wants to stay in rest if at rest and continue in motion if in motion. - When an object is at rest, it wants to stay at rest until it is acted on an unbalanced, outside force--a push. After being moved, the object seeks to keep moving, but it is stopped by friction.

Inversely/indirectly proportional

- When one value decreases at the same rate that the other increases

Weight is a _________, while mass is a __________________ of _______________.

1) Force 2/3) Property of matter

Mass and __________________ are _______________ proportional to another. Thus...

1) acceleration, indirectly 2) As mass increases, acceleration decreases

The gravity on Earth is...

9.81 m/s^2

Unbalanced forces cause

A change in motion and velocity, leading to acceleration

Friction

A force that works against objects to slow them down

Formula for acceleration

Acceleration = final velocity - initial velocity / time

Why does a cart in a roller coaster stay at rest or keep moving?

Because it has inertia (best answer)

How is inertia related to acceleration?

Before and after acceleration occurs, inertia is always at work. It is keeping items at rest still and moving objects in motion. After an unbalanced force is applied to an object, the object moves, overcoming its inertia. This causes a change in velocity, resulting in acceleration.

Newton's 2nd Law states that "unbalanced forces cause objects to accelerate with an acceleration which is directly proportional to the net force and inversely proportional to the mass." What does this really mean?

Big, heavy objects don't move as fast or as easily as smaller, lighter objects.

Use FSSL to solve this: A phone with a mass of 2 kg accelerates 0.6 m/s/s when Milo pushes across a table. How much force did he apply to the phone?

Force = (Mass)(Acceleration) Force = (2 kg)(0.6m/s/s) label Force = 1.2 N

A basic understanding of Newton's 2nd Law is...

Force = (mass)(acceleration) or f = ma

Example of acceleration

Gravity (9.81 m/s^2 on Earth)

How does gravity accelerate?

It accelerates, or speeds up, at 9.8 m/s^2

Which physical property affects the inertia of an object?

Its mass, as more massive objects have greater tendencies to resist a change in their state of motion.

The more ___________ an object has, the more ____________ pulls on it.

Mass, weight

Newton's 2nd Law

The acceleration of an object depends on: - The size of the forces acting upon the object - The mass of the object Force = (mass)(acceleration)

What happens to an object's weight on other planets?

The object will still have the same mass, but it will have a different weight depending on the gravity of the location that they are in

What are two variables we can change to make objects move faster?

Their mass and the force exerted to move them

Is this statement true or false? Velocity is the same thing as acceleration.

This is false, as acceleration is the change in an object's velocity over time.

Is this true or false? A spring scale is used to measure force.

True, because it measures weight--a force.

If people riding a cart on a roller coaster aren't wearing seatbelts when the cart goes downward, in which direction would they move?

UP!

Formula for weight

W=mg, or weight = mass x gravity

Directly proportional

When one value/amount increases, the other also increases at the same rate

Formula for acceleration (using Newton's 2nd Law)

acceleration = force / mass

The opposite of acceleration is

deceleration, or negative acceleration--when an object slows down

w = mg is another form of...

f = ma, or force=(mass)(acceleration) just w = force and gravity = acceleration

As the amount of force applied increases, an object's speed ________________.

increases

Formula for mass

mass = force / acceleration

Upward force is also called

normal force

Both weight and mass are...

quantitative measurements

As the mass of an object increases the object will travel at a __________ rate.

slower