Factors That Affect Motion

Objects are made of matter

Matter is the stuff that makes up everything in the universe.

Mass is the amount of matter in an object.

The mass of an object affects it’s motion.

Inertia affects motion

Inertia is an objects resistance to change motion. The greater the mass of an object, the greater the inertia the object will have.

Example- It is hard move a big object like a semi-truck. It is also hard to stop a semi-truck when it has started moving. This is due to the fact that a semi-truck is very mass and has a lot of inertia.

Momentum

Momentum is the mass and velocity of an object multiplied together. Greater mass and speed cause moving objects to have greater momentum.

Examples – A human that weighs 160 pounds and is running has more

momentum then a human that weighs 160 pounds that is walking.

A truck traveling at 60 mph has a more momentum than a motorcycle driving at 60 mph.

Which object would have greater momentum?

120 lb cheetah running at 60 mph 2000 lb car traveling at 60 mph

3000 lb Jet traveling at 2000 mph 3000 lb truck traveling at 80 mph

2 ounce tennis ball traveling 60 mph 12 lb shot put traveling at 20 mph

Friction is a force

Friction is a force that causes objects to stop moving. Friction happens whenever two objects rub together.

You can feel the friction in the form of heat when you rub your hands together.

Examples of Friction – Air resistance, When you cannot run through the water, a ball rolling to a stop.

What is the real definition of work?

Work – Using a force to move an object over a certain distance.

In order to do work you must exert an effort. Examples of work – Moving your pencil across your

paper. Picking up your books and taking them to math class. Running a lap on the track.

This is not an example of work.

What is energy

Energy is the capacity to do work.

Energy comes in many different forms.

Examples of energy.FoodElectricity

HeatLight

How do humans use energy

Nearly everything you do is considered work. In order to do this we need energy. Humans get their energy from the food we eat.

Examples of how we use energy through work.

Getting dressed, walking up and down stairs, cleaning your room.

Can you think of any other ways you use energy to do work.

Why do we need machines

A machine is something that replaces human effort. Machines make doing work easier.

A car helps us travel far distances quickly. A knife helps cut food easily.

Can you think of any machines that reduce effort for the work we have to complete.

How do machines use energy?

Different machines require different types of energy.

A blender requires electrical energy. A car requires heat energy from burning gasoline. A remote control requires chemical energy from batteries.

Questions you may see on the EOG

What is the tendency of an object to remain at rest or stay in motion?a. inertia

b. gravityc. friction

d. magnetism

What is changed when the speed and mass of an object are increased?a. friction

b. gravityc. inertia

d. momentum

A soccer ball rolls across a grassy field and comes to a stop. What caused the soccer ball to stop?

a. inertiab. friction

c. gravityd. magnetism