# Kinematics and Dynamics - Key terms

### ACCELERATION:

A change in velocity.

### DYNAMICS:

The study of why objects move as they do; compare with kinematics.

### FORCE:

The product of mass multiplied by acceleration.

### HYPOTHESIS:

A statement capable of being scientifically tested for accuracy.

### INERTIA:

The tendency of an object in motion to remain in motion, and of an object at rest to remain at rest.

### KINEMATICS:

The study of how objects move; compare with dynamics.

### MASS:

A measure of inertia, indicating the resistance of an object to a change in its motion—including a change in velocity.

### MATTER:

The material of physical reality. There are four basic states of matter : solid, liquid, gas, and plasma.

### MECHANICS:

The study of bodies in motion.

### RESULTANT:

The sum of two or more vectors, which measures the net change in distance and direction.

### SCALAR:

A quantity that possesses only magnitude, with no specific direction. Mass, time, and speed are all scalars. The opposite of a scalar is a vector.

### SPEED:

The rate at which the position of an object changes over a given period of time.

### VACUUM:

Space entirely devoid of matter, including air.

### VECTOR:

A quantity that possesses both magnitude and direction. Velocity, acceleration, and weight (which involves the downward acceleration due to gravity)are examples of vectors. Its opposite is ascalar.

### VELOCITY:

The speed of an object in a particular direction.

### WEIGHT:

A measure of the gravitational force on an object; the product of mass multiplied by the acceleration due to gravity. (The latter is equal to 32 ft or 9.8 m per second per second, or 32 ft/9.8 m per second squared.)