Ch - 8 (Work & Power) Flashcards

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1
Q

What is work? (In simple words)

A

Transfer of energy due to force

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2
Q

What is power? (In simple words)

A

Rate of transfer of energy (work done per unit time)

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3
Q

What is efficiency? (in simple words)

A

Ratio of useful output and total input

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4
Q

What is work done in simple words?

A

Amount of energy transferred

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5
Q

What is the formula for Work?

A

Work = F x d

E (Energy) = F x d (force exerted in the direction of a force)

Unit: Joules

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6
Q

What is the formula for power?

A

Power = Work (Energy)/Time

Unit: Watts (W)

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7
Q

Define work done.

A
  • the amount of energy transferred when one body exerts a force on another the energy transferred by a force when it moves.
  • Work done = energy transferred
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8
Q

What are the factors affecting the amount of energy transferred by a force?

A
  1. Size - The greater the force, the more work it does.
  2. Distance moved in the direction of the force - the further it moves, the more work it does.
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9
Q

What is work done, measured in?

A

Joules (J)

1J = 1Nm
1000J = 1000 Nm

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10
Q

define power.

A

The rate at which energy is transferred or the rate at which work is done.

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11
Q

What are the important units of power?

A
  • Watts (W)

1 W = 1 J/s
1000 W = 1kW
1000000 W = 1 MW

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12
Q

What is the relationship between work done and energy transferred.

A

Energy transferred (J) = Work done (J)

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13
Q

What happens when a force acts in the direction the object is moving in?

A

Gains energy (usually to its kinetic energy)

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14
Q

What happens when a force acts in the opposite direction the object is moving in?

A

Loses energy (thermal energy store of the surroundings i.e. dissipated as heat or thermal

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15
Q

What is one exam tip to remember?

A
  • Always convert distance into metres
  • Convert force into newtons
  • Convertor done in joules
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16
Q

What happens when work is done?

A
  • that the force does work on the object.
17
Q

When is no work done?

A

When force is applied to an object but doesn’t result in any movement