PHYSICS!!!! objects in motion

5. a body's relative mass or the quantity of matter contained by it, giving rise to a downward force; the heaviness of a person or thing.
8. the extent or amount of space between two things, points, lines, etc.
9. the rate at which an object's position changes, measured in meters per second.
11. a property of matter by which it continues in its existing state of rest or uniform motion in a straight line, unless that state is changed by an external force.
12. a measure of how effectively a system or device converts input energy into useful output energy, often expressed as a percentage.
14. the rate of change of a scalar field with respect to distance, in the direction of the maximum change.
15. a state where an object's motion (both linear and rotational) remains constant over time.
16. the net effect of multiple forces acting on an object, represented as a single force.
17. the speed in combination with the direction of motion of an object.
18. the quantity determining the energy of mass in a gravitational field or of charge in an electric field.

1. the rate of change of velocity per unit of time.
2. an action that changes or maintains the motion of a body or object
3. of or relating to the motion of material bodies and the forces and energy associated therewith.
4. the change in position of an object.
6. the force that attracts a body towards the centre of the earth, or towards any other physical body having mass.
7. the quantity of matter within a given object.
10. the capacity to do work, meaning the ability to exert a force and cause displacement.
13. the principle by which the total value of a physical quantity or parameter (such as energy, mass, linear or angular momentum) remains constant in a system which is not subject to external influence.