Module 3 Definitions and Statements Flashcards

1
Q

Define simple harmonic motion.

A

Force/acceleration is proportional to displacement (from equilibrium position)
(Resultant force) force/acceleration is (always) towards equilibrium position

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2
Q

State the principle of moments

A

(When an object is in equilibrium the) sum of clockwise moments (about a point) = sum of anticlockwise moments (about the same point)

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3
Q

Define velocity.

A

velocity = rate of change of displacement

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4
Q

Define acceleration.

A

acceleration = rate of change of velocity

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5
Q

Define thinking distance.

A

The distance travelled (by the car) from when the driver sees a problem and the brakes are applied

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6
Q

Define work done by a force.

A

work done = force x distance moved in direction of force

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7
Q

Explain the term drift velocity

A

Drift velocity: average mean/net/overall velocity of electron along wire

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8
Q

Define the newton.

A

Force is 1 N when a 1 kg mass has an acceleration of 1 m s–2

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9
Q

Define a couple

A

Two equal but opposite forces

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10
Q

Define the torque of a couple

A

torque = one of the forces x perpendicular distance between the forces

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11
Q

Define density

A

density = mass/volume or ‘density is mass per

(unit) volume’

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12
Q

Define braking distance of a car.

A

The distance travelled (by the car) whilst the brakes are applied and the car stops

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13
Q

State two conditions necessary for an object to be in equilibrium

A

Net / total / resultant force = 0

Net / total torque / moment = 0

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14
Q

Define moment of a force

A

moment = force x perpendicular distance from point / pivot

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15
Q

Define centre of gravity

A

The point where the weight (appears) to act

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16
Q

State the principle of conservation of energy.

A

Energy cannot be created or destroyed; it can only be transferred/transformed into other forms
or
The (total) energy of a system remains constant
or
(total) initial energy = (total) final energy (AW)

17
Q

Define the Young modulus of a material.

A

Young modulus = stress/strain

As long as elastic limit is not exceeded

18
Q

Define the watt.

A

1 J (of work done) per second

19
Q

Define power

A

power = work done/ time
or energy/time
or ‘rate of work done’

20
Q

State Hooke’s law

A

Extension is proportional to force (applied as long as the elastic limit is not exceeded)

21
Q

Explain what is meant by plastic deformation.

A

Material is permanently deformed / longer when stress / force is removed

22
Q

Define ultimate tensile strength of a material.

A

Maximum stress material can withstand (before

fracture)

23
Q

Define the force constant of a spring.

A

force/extension or force per (unit) extension

24
Q

State Hooke’s law for a material in the form of a wire and state the conditions under
which this law applies.

A

the force (needed to stretch a spring is directly) is proportional to the extension (of the spring from its natural length) up to the limit of proportionally

25
Explain what is meant by the elastic limit of the wire
the maximum amount that a material can be stretched (by a force) and still return to its original length when the force is removed
26
State the meaning of | tensile stress
stretching) force (applied) per unit cross-sectional area
27
State the meaning of tensile strain
extension (produced) per unit length
28
State in words Newton’s second law of motion
(Resultant) force (acting on an object) is (directly) proportional to the rate of change of momentum (and occurs in the same direction)
29
Define the impulse of a force
Force x time for which the force acts / duration of collision
30
Define linear momentum.
(linear momentum =) mass x velocity
31
State the principle of conservation of linear momentum
Total momentum is constant/conserved for a closed system/provided no external forces
32
Explain what is meant by an inelastic collision.
Some loss of kinetic energy during collision
33
State Newton’s second and third laws of motion.
Force is proportional to the rate of change of momentum When one body exerts a force on another the other body exerts an equal (in magnitude) and opposite (in direction) force on the first body