# P10, Force And Motion Continued...

• Created by: cieran_10
• Created on: 15-03-18 01:00
Complete the rule: if an object is travelling at a constant speed, its resultant force is...
0.
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When a person drives, what are the driving forces equal and opposite to?
The frictional forces.
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Give the two frictional forces that are acting on a moving car.
Air resistance and the friction between then tyres and the road.
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If an object is travelling at a fast speed, what will happen to the deceleration needed to bring it to a stop in a certain distance?
It will increase.
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What is needed to produce a greater deceleration?
A greater breaking force.
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What will be needed to give a a heavier object a given deceleration?
A greater breaking force.
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What is stopping distance?
It is the distance that a vehicle travel during a driver's reaction time added to the distance it travels under the breaking force/breaking distance.
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What is another name for the reaction time?
The thinking distance.
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Give four factors that could increase the thinking distance of a driver.
Tiredness, the consumption of alcohol, the use of drugs and the usage of a mobile phone.
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What three things can increase the breaking distance of a vehicle?
Poorly maintained roads, poor weather conditions and poorly maintained vehicles.
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Give two examples of vehicle properties that can increase breaking distance.
Worn tyres and/or worn breaks.
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What do ALL moving objects have?
Momentum.
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What two things increase momentum?
A greater mass and a greater velocity.
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What does the law of conservation of momentum say? (2.)
That whenever objects interact in a closed system, the total momentum before the interaction will be the same as afterwards.
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What type of reaction is momentum conserved in and why?
A collision/explosion; there will be no external forces acting on the objects.
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After a collision, what two paths can the two colliding objects take?
One together or in separate directions.
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What is an elastic object?
One that regains its shape when the forces deforming it are removed.
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What is the extension of an elastic object?
It is the increase from the original length of an elastic object to when it is deformed by external forces.
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When plotting a graph to show the extension against the force applied to an object, what will the line of best fir look like and what does this show?
A straight line through the origin, showing that the two things have a directly proportional relationship.
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Why would the line of best fit (on a graph between extension and the force applied to the elastic object) show if it was bending over? (2.)
That the force has become too big, meaning that the limit of proportionality has been exceeded.
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What does Hooke's law say? (2.)
That extension is directly proportional to the force applied, given the the limit of proportionality is not exceeded.
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Complete the rule: the stiffer an object, the greater its...
...spring constant.
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What happens to an elastic object when it is stretched? (2.)
Work is done on it and its elastic potential energy sotre increases.
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What OTHER thing does Hooke's law also apply to?
An elastic object when it is compressed to.
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What happens when the resultant force acts on an object?
The object will accelerate in the direction of the resultant force.
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If an object is not accelerating, what will its resultant force be?
0N.
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What is acceleration?
A change in velocity.
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How can an object change its velocity when reamaining at a constant speed?
By changing its direction.
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What type of force is needed to change an objects' direction?
A resultant force.
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What two things does Newton's second law of motion say?
That acceleration is: proportional to the resultant force on the object (when there is a greater resultant force and the objet receives a greater acceleration) and that it is inversely proportional to the mass of the object.
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What does the acceleration being inversely proportional to the mass of an object mean?
That a bigger object will experience a lesser acceleration.
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What is mass?
The quantity of matter in an object.
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When an object falls freely, what is the resultant force acting on it?
Gravity.
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At what rate will an object falling freely accelerate?
At 10m/s(2.)
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What is weight?
The force of gravity that acts on an object.
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What is acceleration due to gravity?
It is when an object accelerates at 10m/s(2) when falling freely.
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What is gravitational field strength?
It is the gravitational force acting on a 1kg object.
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What are the units of gravitational field strength?
N/kg.
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What force will an object exert when an object falls through a fluid?
A drag force.
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What is a drag force?
It is the force that resists motion.
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Complete the sentence: the faster an object falls, the _____________ its drag force?
Bigger.
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What makes a drag force stop?
When the drag force becomes equal to the weight of the object in question.
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What is terminal velocity?
When an object stops accelerating, the resultant force becomes zero and the object then moves at a constant velocity.
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What is air resistance?
The drag force for an objet falling falling through air.
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## Other cards in this set

### Card 2

#### Front

When a person drives, what are the driving forces equal and opposite to?

#### Back

The frictional forces.

### Card 3

#### Front

Give the two frictional forces that are acting on a moving car.

### Card 4

#### Front

If an object is travelling at a fast speed, what will happen to the deceleration needed to bring it to a stop in a certain distance?

### Card 5

#### Front

What is needed to produce a greater deceleration?