Motion and Resultant Forces Vocabulary

Flashcards covering key vocabulary from lecture notes on Motion and Resultant Forces.

Distance-Time Graph

A graph used to describe the motion of an object and calculate its speed.

Constant Speed (on Distance-Time graph)

Represented by a straight line on a distance-time graph.

Gradient (of Distance-Time graph)

Equal to the speed of a moving object. gradient = ∆y / ∆x, where ∆y is change in distance and ∆x is change in time.

Speed

Calculated from the gradient of a distance-time graph: speed = gradient = ∆y / ∆x

Velocity

The speed of an object in a given direction; a vector quantity with magnitude and direction.

Displacement

Used to calculate velocity because it is a vector quantity, including both magnitude and direction.

Average Speed

Calculated by total distance travelled divided by total time taken. Accounts for non-uniform motion.

Acceleration

Defined as the rate of change of velocity; how much an object's velocity changes every second. It is a vector quantity.

Average Acceleration

Calculated using: a = ∆v / t, where a is average acceleration, Δv is change in velocity, and t is time.

Newton's Third Law of Motion

Whenever two objects interact, the forces they exert on each other are equal in magnitude and opposite in direction.

Resultant Force

A single force that has the same effect on the motion of the object as all the original forces acting together.

Free-Body Force Diagram

Vector diagrams showing the multiple forces acting on a single object.

Newton's First Law of Motion

If the resultant force acting on an object is zero, a moving object will continue to move at the same velocity and a stationary object will remain at rest.

Newton's Second Law of Motion

The acceleration of an object is proportional to the resultant force acting upon it and inversely proportional to the object's mass: F = m × a

Braking Force

The frictional force between the brakes and the wheels of a car; transfers energy and causes deceleration.

Stopping Distance

The total distance travelled during the time it takes for a car to stop in response to some emergency. Sum of thinking distance and braking distance.

Thinking Distance

The distance travelled in the time it takes the driver to react (reaction time).

Reaction Time

A measure of how much time passes between seeing something and reacting to it.

Braking Distance

The distance travelled under the braking force.