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Grade 8 Science > Simple Machines And Mechanisma > Flashcards

Simple Machines And Mechanisma Flashcards

1
Q

What is a lever

A

A lever is a rigid bar that is supported at one point

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2
Q

how is the classified

A

Classified by the locations of the fulcrum the input force and output source.

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3
Q

What is the first class lever and give an example

A

Fulcrum between input force and output force, the output force is always in opposite direction to the input force. Ex.prying the lid off of a paint can

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4
Q

What is the second class lever and give an example

A

Fulcrum at the very end and the output force between the input force and the fulcrum. The input force and output force are in the same direction. Ex. Wheelbarrow

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5
Q

What is a third class lever and give an example

A

Fulcrum at one end the input force is in the middle and the output force is always less than the input force. The distance and speed at the output end of the lever are greater than at the input end. Ex.raking leaves, swinging a baseball hat or hockey stick

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6
Q

How do u determine the mechanical advantage for a lever (IMA)

A

Divide the output force by the input force

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7
Q

What is a pulley?

A

A pulley is made up of a grooved wheel with a rope or cable looped around it. A pulley can change the direction of a force or increase the output force depending on whether the pulley is fixed or movable

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8
Q

What can fixed pulleys do?

A

Only change the direction of force. The output force is equal to the input force so it has an ideal mechanical advantage of 1.

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9
Q

What happens if one end of the rope is fixed and the pulley is allowed to move For a lever?

A

You have a movable pulley

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10
Q

What are the six simple machines

A

Lever, wheel and axe, pulley,inclined plane (ramp), screw snd wedge

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11
Q

What is a wheel and axle and give an example

A

The wheel and axle is made of a shaft(axle) that is attached to a larger disk (wheel) ex.screwdriver, doorknob and bicycle wheels.

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12
Q

What happens when and input force acts on a wheel? And provide an example

A

The output force provided by the axle produces and IMA greater than 1. Ex. Using a screwdriver to turn a screw

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13
Q

How can u determine the IMA In a wheel and axle

A

When the input is applied to the wheel, the IMA can be determined by diving the radius of the wheel by the radius of the axle

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14
Q

What happens when the input force is applied to the axle

A

The mechanical advantage is less than 1 since the input force is closer to the centre of the axle than the output force.

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15
Q

What is an inclined plane

A

A sloping surface on which an object can move

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16
Q

What does the ramp do?

A

The ramp increases the distance an object has to move, but reduces the force needed to move the object.

17
Q

How can the IMA be determined for a plane

A

The length divided by the height of the ramp

18
Q

What is a screw

A

Is an inclined plane wrapped around a rod.

19
Q

What is a thread

A

A continuous inclined plane, the length of the thread is longer than the length of the screw. This difference in length gives the screw it’s mechanical advantage. Also the thread allows it to penetrate into a hard surface

20
Q

What is a wedge and give an example

A

An inclined plane that travels through an object. The longer and narrower the Wedge, the greater it’s mechanical advantage. Ex. Needles, knives and your front teeth

21
Q

What is a mechanism and give examples

A

Two or more simple machines working together. Ex. Scissors are a mechanism since they are made of a lever and wedge

22
Q

What is efficiency

A

The efficiency of a machine measures the useful work done by the machine compared to the work needs to operate it.

23
Q

What happens when parts of a machine touch

A

Friction develops and transforms input energy into heat, therefore extra input force must be Put into the effort to make up for the energy lost to friction.

24
Q

Which machine had less friction (efficiency)

A

Highly efficient machines have less friction, and therefore produce less heat from friction and more input energy is transformed into output work

25
Q

How to u calculate efficiency

A

Useful output work(j) x 100 divided by input work

Grade 8 Science (1 decks)

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