P1.7 Energy and efficiency Flashcards

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1
Q

What is weight measured in?

A

Newtons

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2
Q

What is energy measured in?

A

Joules

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3
Q

What is the definition of 1 joule?

A

Amount of energy required to life a weight of 1 newton by a height of 1 metre is equal to 1 joule

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4
Q

What is the input energy?

A

The energy supplied to the device is called the input energy

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5
Q

What does input energy equal to?

A

Useful output energy + energy wasted

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6
Q

What is the equation for efficiency?

A

Useful output energy transferred by the device/ total input energy supplied to the device

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7
Q

Why can no device be more than 100% efficient?

A

Because you never can get more energy from a machine than you put in

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8
Q

How can you reduce the wasted energy caused by friction between the moving parts?

A

Lubricate the moving parts to reduce friction and reducing the amount of heat produced

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9
Q

How can you reduce the wire getting hot when a current passes through it?

A

Use wires with as little electrical resistance as possible

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10
Q

How can you reduce the thermal energy produced by air resistance causing an object to slow down?

A

Streamline the shapes of moving objects to reduce air resistance

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11
Q

How can you reduce sound created by machinery?

A

Cut out noise by tighten loose parts

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