Flashcards in 1. General Physics Deck (54)

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## How to calculate speed?

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Total distance / time taken

Unit: m/s

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## Interpret speed time graph

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Area underneath = distance travelled

Flat line = constant speed

Straight line going up/down: constant acceleration or deceleration

Acceleration not constant -> curve

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## Interpret distance- time graph

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The slope= speed

The steeper the slope the grater the speed

Flat line= stop

Curve up= slowing down and vice versa

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## What is acceleration

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The change of velocity per second

Unit: m/s2

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## How to calculate acceleration

### Change in velocity / time taken for the change

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## Acceleration of free fall for a body near to the earth?

### Constant acceleration

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## What is velocity?

### Speed in given direction

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## What happen to the motion of a falling body

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Object are slow down by air resistance

Air resistance gets bigger as accelerate

Once air resistance = force of gravity, the object has reached terminal velocity

Object stay at a constant velocity

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## What is terminal velocity

### When a free falling body air resistance force and gravity force is equal and the object will stay at a constant velocity.

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## What is mass?

### A measure of the amount of matters a body contains

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## What is inertia

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An object's resistance to a change in its motion

The greater the mass, the more inertia it has

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## How to calculate weight?

### 1kg = 10N

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## What is density

### How tightly packed matter is and the amount of mass in a given space

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## How to calculate density?

### Mass/ volume

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## What is the density of water and when does an object sink in water?

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Density of water= 1g/cm3

Density of object > density of water => sink

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## How to measure volume of a irregular object?

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Put the object into measuring cylinder with water. When you add the object, it displaces the waters, making the water level rises

The rise= volume of object

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## What is the effect of force?

### Change in size, shape, speed or direction

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## What is elastic

### When an object regains its original shape when the force that deform it are removed -> it is elastic

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## What is elastics limit?

### The limit to which an object can be stretched without being permanently extended

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## What is hooke's law?

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F=kx

K is spring constant, extension is directly proportional to the weight

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## What is the name when the force no longer directly proportional to the extension?

### Limit of proportionality

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## What is resultant force?

### A single force that has the same effect as all the forces acting on the object

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## What happen when resultant force =0

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The object remain at rest if it was already at rest

Continue to move at the same speed and in the same direction if it was already moving

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## How to calculate force?

### Mass x acceleration

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## Describe circular motion

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An object moving around a circular path is acted by a resultant force which is directed towards the cent of the circle

The resultant force is called the centripetal force

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## What is moment?

### Turning force

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## What is moment of the force

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The turning effect of the force

Measured in Newton

Can be either clockwise or anticlockwise

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## How to calculate moment?

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Force x perpendicular distance to pivot

Unit Nm

F x d

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## Describe an object in equilibrium

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No resultant force on it

No resultant turning force on it

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