forces and motion

unit 4 -Force, Motion, and Energy

SWBAT: UNDERSTAND CONCEPTS OF FORCE AND REMEMBER FOR EXAM

Kinetic energy is the energy of motion.

​

There is more kinetic at the lowest point.​

Kinetic Energy

Potential energy is energy that is stored.

​

There is more potential at the highest point.​

​

​

Potential Energy

Potential and Kinetic Energy

Multiple Choice

Potential or kinetic? An electrical current flows in order to provide power to a lamp.

• Potential

• Kinetic

Multiple Choice

Potential or kinetic? A book sitting on a shelf

• Potential

• Kinetic

Hotspot

Where would you find the highest potential energy?

Unbalanced forces are UNEQUAL forces that:

• cause movement

• cause an object to change speed or direction​

​

Unbalanced Forces

Balanced forces are EQUAL forces that either:

• do not cause movement

• cause an object to keep moving at the same speed and in the same direction​

Balanced Forces

Balanced and Unbalanced Forces

Balanced force

Unbalanced force

​Are there forces acting upon it?

Multiple Choice

Balanced or unbalanced? Sliding a box.

• Balanced

• Unbalanced

Multiple Choice

Balanced or unbalanced? the picture on the wall

• balanced

• unbalanced

Calculating Speed

To calculate speed:

​

Speed= Distance/Time​

​

D

______________

S T

Multiple Choice

A man was training for a marathon. One afternoon he jogged 18 miles in 3 hours. Find the speed by calculating distance divided by time.

• 20 mph

• 15 mph

• 54 mph

• 6 mph

Multiple Choice

Energy of motion.

• Mechanical

• Electrical

• Kinetic

Finding net force

• Imagine two siblings pushing on each side of a door

• One person is trying to open it, and the other to keep it closed

• But the big sibling, being in high school, is stronger than the other

• The older kid pushes closed with a force of 60N, while the younger kid pushes open with a force of 40N

• Because the forces are going in opposite directions, they cancel-ish.

• Opposite forces subtract: 60N-40N= 20 N

• The door was pushed closed with a net force of 20 N.

Multiple Choice

Calculate the Net Force. 

• 60N, Left 

• 40N, Right 

• 0N

• 60N, Right

Multiple Choice

What is the net force?

• 20 N 

• 0 N 

• 400 N 

• 40 N 

What is inertia?

• Inertia is the tendency of objects to resist acceleration (acceleration is a change in motion, as in speeding up or slowing down).

• The amount of inertia an object has depends on its mass.

• Just like with gravity, more mass means more inertia.

• Because of inertia, objects at rest (not moving) tend to remain not moving, and objects that are moving tend to keep moving, unless acted on by a force.

• On earth there is usually forces acting against motion (friction)

Multiple Choice

What kind(s) of objects have inertia?

• all objects with mass
• only objects at rest
• only objects in motion
• only objects whose motion is being changed

Multiple Choice

Because of inertia, a resting object will remain at ________.

• rest

• a constant speed

• school

• inertia 

Multiple Choice

Objects with greater _________ also have greater inertia.

• speed

• mass

• temperature

• friction

Multiple Choice

The tendency of an object to resist a change in motion is...

• inertia

• kinetic energy

• vector

• net force

Newtons 2nd Law

F=MxA

Force - 10N

Mass -5kg

A?

F

M A

Multiple Choice

Which object would require the most amount of energy, or force, to set it into motion?

• a small plant

• a refrigerator

• a school bus

• a bowling ball

Multiple Choice

What is the name of the unit you use to measure force?

• neutron

• newton

• nucleus

• norton

Multiple Choice

What is an example of friction?

• slipping on a patch of ice

• dropping a book on the floor

• working on a computer

• wind blowing against you as you walk

Multiple Choice

How is velocity different from speed?

• Velocity is when an object goes in reverse.

• Velocity is the direction an object moves in, and it has nothing to do with speed.

• Velocity is speed and direction together.

• Velocity is not at all different from speed

Multiple Choice

What does friction do to a moving object?

• makes it rise

• slows it down

• speeds it up

• all the above

The Law of Acceleration

The weight of an object will change how much force is needed for it to move or accelerate.

Example:

If you push against a feather and a rock with the same force, the feather will go a farther distance since it is lighter. The rock would need more force to go the same distance.

Multiple Choice

What object would need more force to accelerate?

• A bowling ball

• A golf ball

• A bouncy ball

• A baseball

The Law of Action and Reaction

Every action has an equal and opposite reaction.

Example:

When a person pushes against a wall, the wall will push back with an equal force in the opposite direction

Multiple Choice

As a car's tires push against the road, what pushes back on the car's tires?

• The driver

• The road

• Gravity

Multiple Choice

Two students are in a baseball game. The first student hits a ball very hard and it has a greater acceleration than the second student who bunts the ball lightly.

• Newton's 1st Law

• Newton's 2nd Law

• Newton's 3rd Law

Multiple Choice

The larger the mass you have the _____ force you need to change its motion.

• more

• less

Multiple Choice

What is Newton's 2nd Law?

• Every action has an equal and opposite reaction

• An object at rest stays at rest, an object in motion stays in motion.

• F = ma

• Friction

Multiple Choice

What is Newton's First Law

• F=ma

• Every action has an equal and opposite reaction

• An object at rest stays at rest, an object in motion stays in motion. 

• Friction