P10 Flashcards

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1
Q

What is inertia

A

The tendency of objects to continue in their state of rest or of uniform motion is called inertia

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2
Q

What is newton’s first law

A

If the resultant force acting on an object is zero and:
The object is stationary, the object remains stationary
The object is moving, the object continues to move at the same speed and in the same direction. So the object continues to move at the same velocity

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3
Q

What is newtons second law

A

The acceleration of an object is proportional to the resultant force acting on the object, and inversely proportional to the mass of the object.

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4
Q

Newtons 3rd law

A

Whenever two objects interact, the forces they exert on each other are equal and opposite

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5
Q

What js the stopping distance

A

The stopping distance of a vehicle is the sum of the distance the vehicle travels during the driver’s reaction time (thinking distance) and the distance it travels under the braking force (braking distance).
For a given braking force the greater the speed of the vehicle, the greater the stopping distance

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6
Q

What is the reaction time for typical person

A

values range from 0.2 s to 0.9 s

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7
Q

How can a drivers reaction time be affected

A

A driver’s reaction time can be affected by tiredness, drugs and alcohol. Distractions may also affect a driver’s ability to react

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8
Q

How can the braking distance of a vehicle be affected

A

The braking distance of a vehicle can be affected by adverse road and weather conditions and poor condition of the vehicle
Adverse road conditions include wet or icy conditions.
Poor condition of the vehicle is limited to the vehicle’s brakes or tyres

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9
Q

What happens to the energy of a vehicle when a force is applied to the brakes

A

When a force is applied to the brakes of a vehicle, work done by the friction force between the brakes and the wheel reduces the kinetic energy of the vehicle and the temperature of the brakes increases

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10
Q

Hiw does speed affect braking force

A

The greater the speed of a vehicle the greater the braking force needed to stop the vehicle in a certain distance

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11
Q

How is deceleration inceased and what can it lead to

A

The greater the braking force the greater the deceleration of the vehicle. Large decelerations may lead to brakes overheating and/or loss of control

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12
Q

What is the equation for momentum

A
momentum = mass × velocit y
p = mv
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13
Q

How does momentum change after an event

A

In a closed system, the total momentum before an event is equal to the total momentum after the event
This is called conservation of momentum

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14
Q

What is the equation for a force that is acting on a moving object

A

F = change in momentum/ time
F = mv - mu/ t
Force equals the rate of change in momentum

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15
Q

How do safety features in cars work

A

E.g air bags, seat belts, crash helmets

Prolong impact time so decreases the rate of change in momentum

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16
Q

How is the extension of a spring linked to the force applied

A

The extension of an elastic object, such as a spring, is directly proportional to the force applied, provided that the limit of proportionality is not exceeded

17
Q

Equation for force on an elastic object

A

force = spring constant × extension

F = k x e

18
Q

How is energy transferred throughout a spring

A

A force that stretches (or compresses) a spring does work and elastic potential energy is stored in the spring. Provided the spring is not inelastically deformed, the work done on the spring and the elastic potential energy stored are equa

19
Q

Equation for elastic potential energy

A

elastic potential energy = 0.5 × spring constant × extension^2
E = 1/2 x k x e^2