Force & Motion

Force & Motion

How do we know something is in motion or if we're just seeing things?

How is Motion Described?

• Motion is an object's change in position relative to a reference point. Whenever your position changes, you are in motion.

• Position is the location of an object.

• Reference Point is a place or objet to which another location is compared.

Getting Somewhere

Another way to describe motion is to measure it's displacement. Whenever an object changes position, it is displaced by a certain distance.

Displacement is the straight-line distance between a starting point and an end point. The displacement is the same no matter what route is traveled.

Multiple Choice

Owen walks 3 meters to his friends house and then they walk 5 meters to Sonic to get drinks. What is his displacement?

• 5 meters

• 8 meters

• 3 meters

• 8 miles

Forces

• A force is a push or pull

• Forces are measured in Newtons.

• Newtons are the SI unit for measuring force

• Force is a vector quantity, which means it has both size, or strength, and direction.

• Forces therefore, have the ability to make things move.

Types of Forces

• Friction is a force that opposes the motion between two surfaces that are in contact.

• Gravity is the universal attraction, or pull, that exists between all objects.

• Magnetism is a pulling force using metals

• Balanced forces are a set of forces that cancel out one another.

• Unbalanced forces are a set of forces acting on an object that do not cancel one another out.

What is the net force?

When forces are unbalanced, the motion of an object changes. Unbalanced forces can make an object start moving, speed up, slow down, or change direction. We can calculate the unbalanced force to figure out how much it will move.

Multiple Choice

An object changes direction. Are the forces acting on the object balanced or unbalanced? Explain.

• Unbalanced

• balanced

Multiple Choice

A football player was running down the field with 10N of force when an opposing player hits him and slows him down 8N. What is the net force?

• 2N

• 10N

• 18N

• 2pmh