The Basics of FORCES Why are forces so

The Basics of FORCES

Why are forces so important?

So what exactly is a force and how do we measure it?

Forces can be a push

Forces can be a pull

A force is a push or pull, or any action that has the ability to change motion.

Forces have Size and direction

The tool to measure force is a spring scale.

Force can be measured in pounds or Newtons. One pound of force equals 4. 48 newtons.

Some examples of forces are: Friction Tension Buoyancy Gravity Compression

Lets focus on the details Buoyancy Friction Gravity Newton’s laws

Buoyancy is the upward force created by liquids Archimedes principle: the buoyant force is equal to weight of the water displaced.

Which is more buoyant, the lemon or the lime? Lemon because it floats on top

Gravity Pulls objects with mass together More mass=more gravity Closer together=more gravity

Why would you weigh less on the moon than earth? The moon has less mass so it has less gravity

Hector weighs 60 kg on Earth what is his weight if he went to the moon? 10 kg What is his mass? 60 kg

The force that always acts opposite to the direction of motion Friction

It would be easiest ride your bike across A: gravel B: sand C: the grass D: a side walk

Which arrow is the force of fiction? A B D C

Which arrow is the force of fiction? A-Gravity B-engine D-Friction C-Buoyant force

Newton’s First Law of Motion Part 1: An object at rest remains at rest unless acted on by an unbalanced force

Newton’s First Law of Motion Part 2: An object in motion remains in motion at constant speed and in a straight line unless acted on by an unbalanced force

The more mass an object has the more inertia it has. True or False

Newton’s Second Law of Motion The acceleration of an object depends on the mass of the object and the amount of force applied Part 1: Acceleration depends on mass Part 2: Acceleration depends on force

What happens when the force increases? The stronger the force on an object, the greater its acceleration.

What happens if the mass is increased? There must be more force to keep the same acceleration 5 N 8 N

1. Archimedes’ principle says that the buoyant force is equal to_______ The weight of the water displaced

2. The gravitational force between each planet and the Sun is A: the same because it is only affected by the gravity of the Sun B: larger for planets farther from the Sun because more force is needed to keep them in orbit C: determined by the mass of the Sun, the mass of the planet, and the planet’s distance from the Sun.

3. The cube has force of gravity 10 Newtons acting on it. What is the Buoyant force? A: 10 Newtons B: more than 10 Newtons C: less than 10 Newtons D: not enough information

Name that law 4. If a driver turns a corner too quickly your body leans sideways 1 st

Name that Law 5. A bowling ball knocks down a set of pins and keeps rolling 1 st

Name that Law 6. A boy wants to travel faster on his bike so he peddles with more force 2 nd

7. An object weights 35 n in the air and 14 n in water. What is the Buoyant force? 35 -14= 21 Newtons

8. What is the net force? 20 N 30 N

What is the net force? 20 N

9. What is the net force? 20 N 30 N

What is the net force? 10 N

10. How many of these are forces? Inertia Mass Friction Buoyancy Newtons Weight Compression Tension Equilibrium Distance Gravity Normal