P10 - Forces and Motion Flashcards

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1
Q

What is Newton’s First Law of Motion

A

If the resultant force on an object is 0, then the object will either remain stationary or continue at a constant velocity

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2
Q

What is Newtons Second Law of motion

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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3
Q

Equation for Newtons Second Law

A

F = ma
Force = mass x acceleration

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4
Q

What is the inertial mass

A

A measure of how difficult it is to change the velocity of an object
A large inertial mass means a large force is needed to produce a given acceleration

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5
Q

What is Newtons Third Law of Motion

A

Whenever two forces interact, the forces they exert on each other are equal (im magnitude) and opposite (in direction)

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6
Q

What forces act on a skydiver jumping out of a plane

A
  1. Initially, the only force is weight due to gravity
  2. The diver accelerates towards the ground
  3. They experience air resistance
  4. As the velocity increases, so does the air resistance
  5. Soon, they are balanced, the velocity stays constant (TERMINAL VELOCITY)
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7
Q

What is the total stopping distance

A

The total distance from when the driver thinks to stop to the position where the car stops
It can be divided into thinking distacne and breaking distance

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8
Q

What is the thinking distance and factors that can affect it

A
  • The distance travelled by the car during the reaction time
  • Tiredness, alcohol, certain drugs and distraction can all increase the reaction time
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9
Q

What is the the stopping distance and factors that can affect it

A
  • The distacne from applying the brake to the car stopping
  • Wet or icy conditions, how worn the tyres are and how worn the brakes are all affect braking distance
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10
Q

Equation for momentum and do moving, stationary or both have it

A
  • Only moving objects have momentum
  • p = mv
  • Momentum (kg m/s) = mass x velocity
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11
Q

What is the conservation of momentum

A

In a closed system, the total momentum before an event is equal to the total momentum after an event

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12
Q

How is an airbag a good safety feature

A
  • When you crash, the change in momentum of a car is rapid which can be fatal
  • However, airbags increase the impact time after the crash that the change in momentum has to act
  • Thius reduces the force you experience as force = change in momentum/time
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13
Q

What is inertia

A

The tendency of an object to remain in a steady state e.g. resting or uniform velocity

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14
Q

typical values for walking, running and cycling

A
  • Walking ≈ 1.5m/s
  • Running ≈ 3m/s
  • Cycling ≈ 6m/s
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