Mechanics Flashcards

1
Q

Acceleration

A

Rate of change of speed

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1
Q

Straight line —- on a distance-time graph

A

Stationary

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2
Q

Straight line —- on a speed-time graph

A

Constant speed

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3
Q

Force

A

A push or a pull. Measure in newtons (N)

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4
Q

Weight force

A

Due to gravity, always acts straight down

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5
Q

Support force

A

When an object pushes down a surface, the surface pushes back. Always at 90 degrees.

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6
Q

Thrust force

A

A push force. Eg from an engine

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7
Q

Friction force

A

The force that opposes motion. Always opposite direction to motion.

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8
Q

Buoyancy force

A

The upward force from a fluid (water or air)

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9
Q

Lift force

A

The upward push on a wing due to its motion through the air

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10
Q

Tension force

A

A pulling force eg from a rope or chain

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11
Q

Mass (m)

A

The amount of matter in an object, measured in kg, does not change if the object changes position

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12
Q

Weight (W)

A

Force of gravity acting upon an object. It is measured in newtons (N). It may change if the object changes position.

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13
Q

What does the force of gravity depend on?

A

The mass of the object (heavier=stronger) and the distance between the centre of the objects (closer=stronger)

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14
Q

What is a gravitational field?

A

Every object is surrounded by a force field known as a gravitational field.

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15
Q

What do lines on a gravitational field represent?

A

The direction of the gravity force that would act on a mass placed at that point, the relative strength of the gravitational field (closer=stronger)

16
Q

What is a free-body diagram?

A

A diagram is a drawing that shows all the forces acting on an object. Arrows represent the size and direction of all forces acting.

17
Q

What happens if the net forces are balanced?

A

Object will be stationary or constant speed

18
Q

What is Newton’s first law?

A

An object continues in uniform motion in a straight line or at rest unless a net force acts upon in

19
Q

What is Newton’s second law?

A

The net force on an object is proportional to the acceleration of the object. Shown by F=ma.

20
Q

What is Newton’s third law?

A

For every action on one object, there is an equal but opposite reaction on another object.

21
Q

What are the two types of friction?

A

Solid friction and fluid resistance

22
Q

What is solid friction?

A

When two solid objects rub against each other, the surface aren’t completely smooth so solid friction occurs. The strength depends on the smoothness of the two surfaces.

23
Q

What is fluid resistance?

A

When an object moves through a fluid. Also known as drag or air resistance. Depends on size /shapeof object, viscosity of liquid and speed of object.

24
Q

Why is friction unwanted?

A

More work needs to be done to overcome forces, heats up objects, damage the surfaces due to wear

25
Q

Why is friction useful?

A

Heats up surfaces, grips on a surface

26
Q

As the speed of an object (falling) increases, what happens to the size of the air resistance?

A

It increases

27
Q

What is terminal velocity?

A

When forces on a falling object are balanced and object is falling at a constant speed.

28
Q

What is energy?

A

The capacity to do work

29
Q

Conservation of energy rule

A

Energy cannot be created or destroyed, only converted to one form from another.

30
Q

Why will a falling object never reach the calculated speed?

A

Some of the kinetic energy will be converted into heat energy due to friction.

31
Q

What is work?

A

When a force moves an object for some distance, we say work is done on the object by the force

32
Q

What is work equal to?

A

The amount of energy gained or lost

33
Q

What is power?

A

The rate of doing work. The faster, the more powerful