P8 Forces Flashcards

1
Q

what are scalar quantities?

A

Quantities with magnitude only
They do not have direction

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2
Q

what is a vector quantity?

A

quantities which have both direction and magnitude

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3
Q

what is displacement?

A

distance in a specific direction

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4
Q

how can vectors be represented?

A

using an arrow.
the length represents the magnitude and the direction of the arrow represents the direction

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5
Q

what is a force?

A

a push or a pull that acts on an object due to the interaction with another object

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6
Q

what type of quantity is a force?

A

a vector

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7
Q

what is the unit of force?

A

N (newton)

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8
Q

what is a contact force?

A

when the two objects are physically touching

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9
Q

what is a normal contact force?

A

when two objects are in direct contact with one having a force of weight and the other providing an upwards force to the other object.

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10
Q

what in a non-contact force?

A

when the two objects are physically separated

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11
Q

what are some examples of non-contact forces?

A

gravitational force, electrostatic force, magnetic force

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12
Q

what is mass?

A

how much matter an object has. It does not depend on where the object is

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13
Q

what is the weight of an object?

A

the force acting on it due to gravity. this is dependant of were an object is

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14
Q

what is g?

A

the gravitational field strength of a location. it is a measure of the force of gravity in a particular location

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15
Q

what is the formula for weight?

A

W = m x g

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16
Q

how are weight and mass related?

A

they are directly proportional
weight = k x mass

17
Q

where does weight act on an object?

A

on a single point known as the centre of mass

18
Q

what is the resultant force?

A

a single force that has the same effect as all the original forces acting together

19
Q

what happens when the resultant force is 0?

A

the forces are balanced so the object is either stationary or moving at constant speed

20
Q

what is a free body diagram?

A

when the object involved is shown as a point
the forces are drawn as arrows from the point

21
Q

what is a vector diagram?

A

a scale drawing showing all of the forces involved

22
Q

what is resolving of a force?

A

when a single force is broken down (resolved) into component forces at right angles to each other

23
Q

what is work?

A

when energy is transferred by a force

24
Q

what is the formula for work?

A

W = F x s (distance)

25
Q

what must the distance be when calculating work done?

A

it must be in the line of action of the force
(the distance must be in the same direction of the force ie. use the vertical distance travelled for gravity which is exerted vertically)

26
Q

what does 1 newton metre equal?

A

1 newton metre of work = 1 joule

27
Q

what is a moment?

A

the turning effect of a force

28
Q

what is the equation for moments?

A

Moment = F (force) x d (distance)

29
Q

what is the unit for a moment?

A

Nm (newton-metre)

30
Q

what does the distance have to be when calculating the moment of a force?

A

perpendicular from the line of action of the force to the pivot

31
Q

what is the pivot?

A

where the turning effect of a force is centred

32
Q

what is happening when two moments are balanced?

A

the anticlockwise moment = clockwise moment
so a lever does not turn in one direction (it is balanced)

33
Q

why do some objects topple?

A

the weight of an object comes directly from the centre of mass.
when the object is turned, there comes a point where the line of action of the force lies outside the base of the block and an unbalanced resultant/moment acting on the object.
this causes the object to fall

34
Q

what is a force multiplier?

A

a lever used so that a weight or force can be moved by a smaller force

35
Q

what are gears used for?

A

transmitting the turning effect of a force

36
Q

what does the turning effect of a gear depend on?

A

the distance between the edge of the gear and the centre (radius)

37
Q

why is the work done by two gears of different sizes the same?

A

the smaller gear rotates more times than the larger one while the larger one has a greater turning effect

38
Q

what does a low gear (small to big gears) give?

A

it gives a low speed and a high turning effect

39
Q

what does a high gear (large to small gear) give?

A

it gives high speed and low turning effect