BIG IDEA #1

A force is an interaction between

two objects.

This can either be a push or a pull.

CV1

A cart is being pulled on both sides by string. The cart was pushed to the right by hand and the pictures were taken right after the

push. String 1 is pulling with the same amount of force as string 2.

Constant Velocity, positive direction

CV2

Constant Velocity, negative direction

The cart was pushed to the left by hand and the pictures were taken right after the push.

A cart is being pulled on both sides by string. The cart was initially at rest. String 2 is pulling with more force than string 1.

SU

Speeding Up, positive direction

A cart is being pulled on both sides by string. The cart was initially pushed by a hand to the left. Right after the push the pictures were

taken. String 2 is pulling with more force than string 1.

SD

Slowing Down, positive direction

WHAT IS A SYSTEM?

BIG IDEA #2

A system is a part of the Universe that we are analyzing. The surroundings are the rest of the

Universe.

FBDs for Motion Activity

CV 1 CV 2

FBDs for Motion Activity

SD SU

FBD important note: arrow length

• When you construct an FBD, each arrow (vector) represents a force on one object by another.

• The size of the arrow shows the magnitude or strength of the force. If forces have the same strength, their arrows should be the same length. If one force is stronger, its arrow should be longer than the other force.

Conclusions about Motion Activities…

• What patterns/similarities/differences do you notice? Use evidence from the FBDs as well as your position-time graphs.

• CONCLUSION: Constant V = balanced

Speeding up or slowing down = unbalanced

BIG IDEA #3

Newton’s 1st Law of MotionWhen the forces are balanced, the object’s

velocity doesn’t change (object stays at rest or stays moving at constant speed).

When the forces are unbalanced, the object’s velocity changes (object speeds up or slows down).