10 Science: Motion

acceleration

rate of change in velocity

average speed

total distance travelled divided by time taken

crumple zones

zones in motor vehicles that are deliberately designed to crumple, absorbing and spreading much of the energy transferred to the vehicle during collision

deceleration

a decrease in speed or velocity, where acceleration is in the opposite direction to velocity

displacement

the change in position of an object (from the start to end position)

force

a push, pull or twist applied to one object by another, measured in newtons (N)

inertia

property of objects that makes them resist changes in their motion

instantaneous speed

speed at any particular instant of time

mass

the amount of matter in an object

net force

the net (total or resultant) force of two or more forces acting on an object

newton

unit of force defined as the force required to provide a mass of 1 kg with an acceleration of 1 m/s2

Newton’s First Law of Motion

law that states that an object remains at rest or continues to move with the same speed in the same direction unless acted on by an outside, unbalanced force

Newton’s Second Law of Motion

law that states that the acceleration of an object is equal to the total force on the object divided by its mass

Newton’s Third Law of Motion

law that states that for every action, there is an equal and opposite reaction

scalar quantity

any quantity that is described by a magnitude, but no direction

speed

a measure of the rate at which an object moves over a distance

vector quantity

any quantity that is described by both magnitude and direction

velocity

a measure of rate of change in position, with respect to time, described by a magnitude and direction

weight

the force due to gravity on an object