Flashcards in Modules 3 Definitions Deck (64)

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## Acceleration

### The rate of change of velocity

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## Average Speed

### Distance over time for the entire region of interest

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## Braking distance

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

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## 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.

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## Displacement-Time graphs

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

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## Free-fall

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

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## Instantaneous speed

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

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## 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.

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## Reaction time

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

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## Stopping distance

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

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## Thinking distance

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

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## Velocity-time graphs

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

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## Velocity

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

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## Archimedes' Principle

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

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## Centre of Gravity

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

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## Centre of mass

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

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## 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.

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## Density

### The mass per unit volume of a material.

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## Drag

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

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## Equilibrium

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

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## Free-body diagram

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

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## Friction

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

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## Moment of force

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

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## Newton

### The unit of force

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## 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.

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## Normal contact force

### The reaction force between an object and surface

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## Pressure

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

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## 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.

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## 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.

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