P2- Forces Flashcards

1
Q

When two objects interact…

A

They always exert equal and opposite forces on each other.

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2
Q

What is resultant force?

A

The resultant force is a single force that has the same effect as all the forces acting on an object.

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3
Q

When the resultant force is at zero:

A
  • If the object is at rest, it will stay at rest.
  • If the object is moving, it will carry on moving in the same direction and speed.
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4
Q

What is the resultant force of a 5N force and a 8N force acting in the same direction?

A

13N in the same direction.

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5
Q

How can we calculate resultant force?

A

F= m x a

F= force in N.

m= mass in kg.

a= acceleration in m/s2

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6
Q

What happens to the acceleration of an object if the mass increases?

A

Acceleration decreases because a bigger force is needed to give a particular acceleration.

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7
Q

What forces would oppose the driving force of a car?

A

Friction and air resistance.

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8
Q

What is stopping distance?

A

Thinking distance + braking distance.

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9
Q

How can thinking distance be increased?

A

If the driver is:

  • Tired.
  • Under influence of drugs.
  • Under influence of alcohol.
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10
Q

What are forces measured in?

A

Newtons, N.

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11
Q

How can braking distance be increased?

A
  • Poorly maintained roads or bad weather conditions.
  • Condition of car➡️e.g: worn tyres or worn brakes.
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12
Q

What is mass and what is it measured in?

A

Mass is the amount of matter in an object.

An object has the same mass everywhere i.e: Earth or outer space. Mass is measured in kilo grams.

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13
Q

What is weight and what is it measured in?

A

Weight is the force of gravity attracting the mass towards the centre of the Earth. Weight is measured in newtons (N).

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14
Q

What is the equation to calculate the weight?

A

Weight (N)= Mass (kg) x gravitational field strength (N/kg).

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15
Q

What is meant if a falling object has reached terminal velocity?

A

The falling object has reached a steady speed where drag/(air) resistance= weight.

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16
Q

What is the ‘extension’ of a spring?

A

The extension is the difference between the length of the spring and the original length.

17
Q

What is Hooke’s law?

A

The extension of a spring is directly proportional to the force applied to it, provided the limit of proportionality is not exceeded.

18
Q

How can Hooke’s law be written as an equation?

A

F= k x e

F= force applied in newtons (N).

k= spring constant in newtons per metre (N/m).

e= extension in metres (m).

19
Q

Why does making a vehicle more streamlined improve fuel economy?

A

Reduced air resistance.