Modules 3 Definitions Flashcards Preview

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Flashcards in Modules 3 Definitions Deck (64)
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1

Acceleration

The rate of change of velocity

2

Average Speed

Distance over time for the entire region of interest

3

Braking distance

The distance travelled between the brakes being applied and the vehicle coming to a stop.

4

Displacement

The direct distance between and object's starting and ending positions. It is a vector quantity and so has both a direction and a magnitude.

5

Displacement-Time graphs

Plots showing how displacement changes over a period of time. The gradient gives the velocity. Curved lines represent acceleration.

6

Free-fall

An object is said to be in free fall when the only force acting on it is the force of gravity

7

Instantaneous speed

The exact speed of an object at a specific given point.

8

Projectile motion

The motion of an object that is fired from a point and then upon which only gravity acts. When solving projectile motion problems, it is useful to split the motion into horizontal and vertical components.

9

Reaction time

The time taken to process a stimulus and trigger a response to it. It is affected by alcohol, drugs and tiredness.

10

Stopping distance

The sum of thinking distances and braking distance for a driven vehicle.

11

Thinking distance

The distance travelled in the time it takes for the driver to react. It is affected by alcohol, drugs and tiredness.

12

Velocity-time graphs

Plots showing how velocity changes over a period of time. The gradient gives acceleration. |Curved lines represent changing acceleration.

13

Velocity

The rate of change of displacement. It is a vector quantity and so has both a direction and a magnitude.

14

Archimedes' Principle

The upwards force acting of an object submerged in a fluid, is equal to the weight of the fluid it displaces.

15

Centre of Gravity

The single point through which the object's weight can be said to act.

16

Centre of mass

The single point through which all the mass of an object can be said to act

17

Couple

Two equal and opposite parallel forces that act on an object through different lines of action. It has the effect of causing a rotation without translation.

18

Density

The mass per unit volume of a material.

19

Drag

The frictional force that an object experiences when moving through a fluid.

20

Equilibrium

For an object to be in equilibrium, both the resultant force and resultant moment acting on the object must be equal to 0.

21

Free-body diagram

A diagram showing all the forces acting on an object. It is a good starting point to any mechanics problem.

22

Friction

The resistive force produced when there is relative movement between two surfaces.

23

Moment of force

The product of a force and the perpendicular distance from the line of action of the force to the pivot.

24

Newton

The unit of force

25

Newton's Second Law

The sum of the forces acting on an object is equal to the rate of change of momentum of the object. It is also expressed as the net force acting on an object equalling the product of the object's mass and acceleration.

26

Normal contact force

The reaction force between an object and surface

27

Pressure

The force that a surface experiences per unit area. It is measured in pascals (Pa)

28

Principle of moments

For an object to be in equilibrium the sum of the clockwise moments acting about a point must be equal to the sum of the anticlockwise moments acting about the point.

29

Tension

The result of two forces acting on an object that occurs when the resistive and driving forces acting on the object are equal to each other.

30

Terminal velocity

The maximum velocity of an object that occurs when the resistive and driving forces acting on the object are equal to each other.