# Force Concepts

## Initial perceptual naive misconceptions (any age)

### Misconceptions (Explanations, Naive understanding, Misconceptions, or Perceptual responses)

1. Force continues to push after acting on the object. Like when it is gliding.
2. An object a person is sitting or standing on doesn’t push back with equal force. The person is just resting on it. The reaction force doesn’t exist.
3. A force is put on a projectile when it is launched and the force gradually decreases causing the object to slow and eventually stop when the force is used up. A thrown rock, hit ball, bullet.
4. Friction is not a force.
5. Friction slows objects or doesn’t allow them to move. Friction can use up the force.
6. Friction is only present when something is rubbing against a moving object.
7. If something is moving there must be a greater force on it.
8. If you jump the force is greater than gravity. If an airplane is rising, then lift must be greater than gravity.
9. The faster an object is moving the greater the force on it.
10. Objects move in the direction of the strongest force.
11. When a car brakes, the passengers experience a sudden forward force.
12. Objects in motion can curve and make centrifugal force.
13. It is possible to start and stop without accelerating or decelerating.

#### Gravity

1. Weightlessness means no gravity.
2. Heavier objects fall faster than lighter ones.
3. Gravity is a very strong force.
4. There is no gravity in space, on the moon, in a vacuum,
5. Gravity is caused by Earth’s spin, air pressure, push from above.
6. Gravity is weaker under water.
7. Gravity is stronger the higher you are in a building or mountain that’s why it is easier to fall.
8. Gravity will be stronger the longer and object falls.
9. Shape affects gravity
10. Gravity is weaker the higher you go. That’s why things fall faster the farther they fall.
11. Astronauts are weightless because they are beyond Earth’s gravity.
12. Gravity is the attraction of the larger body. The Earth and me are not attracted by other objects pulling up.
13. Gravity causes objects to fall down through the center of the Earth and out the other side if there was a hole in through the Earth.
14. Gravity pulls objects towards the south pole and if the Earth would not stop it they would go off into space away from the south pole.
15. Gases are not affected by gravity.

#### Weightless

1. Weightlessness is a result of being in space.
2. Weightlessness only happens in a space vehicle.
3. Weightlessness happens with the absence of air.
4. Weightlessness happens when an object leaves Earth.
5. Emptiness or nothingness creates weightlessness.
6. Free fall near Earth does not have weightlessness.
7. There is an additional force involved with free fall.

## Beginning (preschool - 7 years)

### Concepts

1. An object can be moved with a push or pull.
2. The distance of the motion is related to the size of the push or pull.
3. Objects near the Earth fall unless held.
4. Magnets can make some objects move.

## Intermediate (7 years - 11 years)

### Concepts

1. Force, mass, and movement are related.
2. The greater the force, the greater the change of direction.
3. Friction is a force that can slow an object.
4. The Earth's gravity pulls objects toward the center of the Earth.
5. Magnets push or pull other magnets and objects made from iron or cobalt.
6. Electricity can push and pull other objects.

## Literate (11+)

### Concepts

1. An object that is not being subjected to a force will continue to move at a constant speed and in a straight line.
2. If more than one force acts on an object along a straight line, then the forces will reinforce or cancel one another, depending on their direction and magnitude.
3. Unbalanced forces will cause changes in the speed or direction of an object's motion.
4. All objects have a gravitational force that interacts with another objects gravitational force proportional to the masses and distances.
5. Electricity and magnetism can exert a force on each other.

#### Gravity

1. Gravity is the force of attraction between masses.

#### Weight

1. Weight is another name for gravitational force.
2. Weight is the force exerted by an object against a support and is equal to the force exerted by the support on the object.
3. Weightlessness is never absolute, there is always some, maybe very small weight.
4. Gravitational force and weight being the same, decrease with increasing distance from the Earth?

#### Weightless

1. Weightlessness is the result of no force being excerted on the body. It can be achieved by motion that exceeds gravity and puts the body in a certain free fall. It can also be achieved by being in a position that is far enough away from gravitational forces of massive bodies.

Relative position and motion - see Process skills - relative position and motion