PHY 4 - Equilibrium Flashcards

1
Q

What is Torque ?

A

(L)

The rotational motion of an object about an axis caused by the forces perpendicular to the axis.

L (NM) = Force (N) x Distance (M)

NB. Distance = distance from Pivot point

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2
Q

In which direction does positive torque turn ?

A

Anticlockwise

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3
Q

In which direction does negative torque turn ?

A

Clockwise

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4
Q

What is Newton’s First law ?

A

Objects in motion or at rest tend to remain as such unless acted on by an outside force.

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5
Q

What is Inertia ?

A

Resistance to motion

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6
Q

What is momentum ?

A

A vector quantity (M)

M is also a measure of the force needed to stop or change the direction of an object.

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7
Q

Describe Linear Momentum

A

Linear M is the tendancy of an object to maintain motion in a straight line.

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8
Q

What is an Impulse ?

A

(I)

A measure of the change of momentum of an object

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9
Q

What are the two different types of Collision ?

A
  1. Elastic
  2. Inelastic
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10
Q

Describe an Elastic Collision, and give an example.

A

Objects rebound off each other. There is conservation of momentum and KE.

E.g. 2 rubber balls collide

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11
Q

Describe an inelastic collision, and give an example

A

Objects stick together.

There is also conservation of momentum, but not of KE (which is lost as heat or sound, so total energy is conserved).

E.g. Two cars colliding

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12
Q

Describe the equation for the conservation of momentum in a collision

A
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13
Q

What do you need to know in order to solve problems involving Torque ?

A

Translational Equilibrium:

Σ upward force = Σ downward force

Rotational Equilibrium:

Σ positive torque = Σ negative torque

N.B. If you have two unknowns, take 1 to be the pivot point and it will be eliminated (=0) because torque at pivot point = 0.

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14
Q

What happens when a force acts on an object ?

A

The object undergoes either:

  • Translational motion
  • Rotational motion
  • Complex motion (translational and rotational)
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