Understanding Internal and External Forces

Which of the following is considered an internal force?

• Tension force

• Friction force

• Magnetic force

• Air resistance force

What is the main characteristic of internal forces regarding mechanical energy?

• They have no effect on mechanical energy.

• They keep the total mechanical energy constant.

• They decrease the total mechanical energy.

• They increase the total mechanical energy.

How do external forces affect an object's total mechanical energy?

• They always increase it.

• They can change it.

• They always decrease it.

• They have no effect on it.

When is positive work done on an object?

• When force and displacement are in opposite directions.

• When force and displacement are in the same direction.

• When there is no displacement.

• When the object is at rest.

What happens to an object's mechanical energy when negative work is done?

• The object loses mechanical energy.

• The object gains mechanical energy.

• The object's mechanical energy doubles.

• The object's mechanical energy remains unchanged.