Chapter 4: Mechanics Flashcards

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1
Q

What is a scalar?

A

a quantity that has magnitude but no direction

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2
Q

What is a vector?

A

a quantity that has magnitude and direction

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3
Q

What are some examples of scalars?

A

distance, speed, energy, mass, power, temperature

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4
Q

What are some examples of vectors?

A

displacement, velocity, force (inc. W), acceleration, momentum, electric/magnetic field

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5
Q

To resolve vectors, they should be placed ……….

A

tip-to-tail

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6
Q

When resolving vectors, they should be split into…..

A

a horizontal and vertical component

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7
Q

Parallel vectors of equal magnitude are …..

A

equivalent

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8
Q

What does it mean if an object is in equilibrium?

A

all forces acting on it are balanced
there is no resultant force
an object in equilibrium can be at rest or at constant VELOCITY

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9
Q

What is mass?

A

the amount of matter in an object
measured in kg
it does not change as the strength of the gravitational field changes

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10
Q

What is weight?

A

it is a force
measured in Newtons (N)
it is the force experienced by mass due to a gravitational field, weight does vary according to the size of the gravitational field

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11
Q

What is the formula for weight?

A

W=m*g

g= gravitational field strength (Nkg⁻¹)

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12
Q

What is a moment?

A
  • the turning effect of a force around a pivot

- depends on the force applied from the pivot and the distance from the pivot

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13
Q

What is the principle of moments?

A

for a body to be in equilibrium, the sum of the clockwise moments about any point equals to the sum of the anticlockwise moments around the same point
if the moments aren’t balanced, the object will turn

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14
Q

What is a lever?

A

a structure made of a rigid object rotating around a pivot, in which an effort force works against a load force
they increase the distance from a pivot so less force required to get the same moment

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15
Q

What is a couple?

A

a pair of forces of equal size which act parallel to each other but in opposite directions, doesn’t cause a resultant linear force, but does produce a moment

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16
Q

What is the centre of mass?

A

the COM of an object is the single point that you can consider its whole weight to act through (whatever its orientation)

17
Q

When will an object topple over?

A

an object will topple if the line of action of its weight falls outside the base area, because a resultant moment occurs, which provides a turning force

18
Q

Where is the centre of mass of a regular, uniform object?

A

the centre of mass will be the centre of the object

19
Q

What makes an object unstable?

A

if its centre of mass is higher
and if it has a small base area
an object will be stable if it has a low centre of mass and a wide base area