P2.3 Flashcards

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1
Q

How do you change the shape of an object?

A

Compress
Strength
Bend

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2
Q

How many forces are needed to change the shape of an object?

A

Two or more

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3
Q

Why are certain materials described as plastic?

A

If they do not return to their original shape when stretched

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4
Q

What does it mean in science if a materials is elastic?

A

They return to their original shape when the forces are removed

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5
Q

What does a graph of force against extension look like?

A

Linear until a certain point

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6
Q

What is the point called in a extension against force graph when it is no longer a linear relationship?

A

The limit of proportionality or the elastic limit

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7
Q

What happens to a spring after the elastic limit?

A

It doesn’t return to its original shape - permanently deformed

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8
Q

What is Hooke’s Law?

A

The extension of a spring is proportional to the force until you reach the limit of proportionality

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9
Q

What is the equation for the force exerted by a spring?

A

Spring constant (N/m)
———————————
Extension (m)

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10
Q

What are the units for the force exerted by a spring?

A

Newton (N)

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11
Q

What part of the graph is known as the spring constant?

A

The gradient of the linear section of the force against extension graph

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12
Q

What does the spring constant determine?

A

How difficult it is to stretch the spring

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13
Q

What is the formula for energy transferred in stretching?

A

0.5 x spring constant (N/m) x (extension (m))^2

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14
Q

What is “energy transferred” in a spring equal to?

A

Work done

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15
Q

What happens when you stretch a material that isn’t a spring?

A

The relationship between extension and force isn’t linear

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16
Q

What is a gravitational field?

A

A region where mass experience an attractive force

17
Q

What is the formula for gravitational force?

A

Mass (Kg) x gravitational field strength (N/Kg)

18
Q

What are the units for gravity force?

A

Newtons (N)

19
Q

What is gravity field strength or gravity constant?

A

The measure of the force on 1kg mass when it is in a gravitational field due to another mass

20
Q

What is the formula for weight?

A

Mass (Kg) x Gravitational Field Strength (N/Kg) = 10N/Kg

21
Q

What is weight and what are the units for it?

A

The force of earth on an object - measured in Newtons (N)

22
Q

What is the formula for resultant force?

A

Resultant force (N) = Mass(Kg) x acceleration due to gravity (m/s^2) = (10m/s^2 on earth)

23
Q

What is acceleration due to gravity on earth?

A

10m/s^2 (9.81 to be exact)

24
Q

What is the formula for gravitational potential energy (gpe)?

A

Mass (Kg) x height (m) x gravitation field strength (N/Kg) =10N/Kg

25
Q

What is a moment?

A

The turning effect of a force

26
Q

What is the formula for moment?

A

Force (N) x distance (M)

27
Q

What is the principle of moment?

A

An object is balanced when the anti-clockwise moment is equal to the clockwise moment

28
Q

What is the formula for mechanical advantage in levers?

A

Load - force the lever exerts on the load
———————————————————
Effort - force you exert

29
Q

What is the rule in pivots?

A

Distance x effort = distance x load

30
Q

What is a load?

A

The force that the lever exerts on the load

31
Q

What is effort?

A

The force you exert on the lever

32
Q

How do cogs transmit forces

A

If you rotate a small cog, it will make the larger cog rotate

33
Q

What is the ratio between large and small cogs?

A

The force x distance is the same for all cogs

34
Q

What is the formula for pressure?

A

Force normal to the surface (N)
———————————————
Area of that surface M^2)

35
Q

What is a hydraulic machine?

A

A machine made of two pistons connected by a pipe which has the same pressure throughout it

36
Q

How do you calculate pressure in a hydraulic machine?

A

Force Force
——— = ————
Area Area