Forces Flashcards

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1
Q

What do scalar quantities have?

A

MAGNITUDE (size) only. DO NOT have a DIRECTION.

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2
Q

Give 3 examples of scalar quantities.

A

Any 3 from: mass, temperature, speed, energy, distance and time

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3
Q

What do vector quantities have?

A

MAGNITUDE and DIRECTION.

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4
Q

Give 3 examples of vector quantities.

A

Any 3 from: displacement, weight, force, velocity, acceleration and momentum.

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5
Q

What two categories can forces be divided into?

A

Contact forces and non-contact forces.

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6
Q

What is a force?

A

A force is a PUSH or a PULL that acts on an object due to the INTERACTION with another object.

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7
Q

What is a contact force?

A

A contact force where TWO OBJECTS are PHYSICALLY TOUCHING.

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8
Q

Give an example of a contact force.

A

Any 1 from: friction, tension and air resistance.

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9
Q

What is a non-contact force?

A

Where to the TWO OBJECTS are PHYSICALLY SEPARATED.

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10
Q

Give an example of a non-contact force.

A

Any 1 from: gravitational force, electrostatic force and magnetic force.

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11
Q

What is meant by mass?

A

The mass of an object tells us how much MATTER the object has IN IT.

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12
Q

What is meant by weight?

A

The weight of an object is the FORCE acting on it due to GRAVITY.

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13
Q

What equation do you use to calculate weight?

A

weight (N) = mass (kg) x gravitational field strength (N/kg) W = m g

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14
Q

What can we say about weight and mass of an object?

A

The weight of an object is DIRECTLY PROPORTIONAL to the mass of the object. Weight ∝ Mass

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15
Q

What is meant by gravitational field strength?

A

It is a measure of the force of GRAVITY in a particular LOCATION.

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16
Q

What is meant by altitude?

A

HEIGHT above the ground.

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17
Q

What is key about inelastic material?

A

They DO NOT return to their original length when the forces are removed (INELASTIC DEFORMATION).

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18
Q

What equation do we use to calculate the force needed to stretch an elastic object?

A

Force (N) = spring constant (N/m) x extension (m)

19
Q

What equation do we use to calculate speed?

A

speed (m/s) = distance / time

20
Q

What does the gradient of a distance time graph tell us?

A

Tells us the object’s SPEED.

21
Q

How do you work out the gradient?

A

gradient = distance travelled / time taken

22
Q

What equation do we use to calculate acceleration?

A

………………………….2

acceleration (m/s) = change in velocity (m/s) / time (s)

23
Q

What does the gradient of a velocity time graph tell us?

A

The ACCELERATION of the object.

24
Q

What does a horizontal line show us?

A

That the object is travelling at a CONSTANT VELOCITY.

25
Q

What does an upward sloping line tell us?

A

That the object is ACCELERATING.

26
Q

What does a downward sloping line tell us?

A

That the object is DECELERATING.

27
Q

What does the total area under the graph tell us?

A

The DISTANCE TRAVELLED in a specific direction (displacement).

28
Q

What is key about Newton’s First Law of Motion in relation to resultant force?

A

The VELOCITY of an abject will only change if a RESULTANT FORCE is acting on the object.

29
Q

What is Newton’s 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.

30
Q

What is Newton’s third law of motion?

A

Whenever two objects interact, the FORCES they exert on each other are EQUAL and OPPOSITE.

31
Q

What is meant by the stopping distance?

A

Is the total DISTANCE travelled from when the driver first spots the obstruction to when the car stops.

32
Q

What is meant by the thinking distance?

A

The distance travelled by the car during the driver’s REACTION TIME.

33
Q

What is meant by the reaction time?

A

The time taken for the driver to spot the obstruction, make a decision and then move their foot to the brake.

34
Q

What is meant by the breaking distance?

A

It is the distance the car travels from when the driver APPLIES THE BRAKES to when the car STOPS.

35
Q

What is the stopping distance made up of?

A

The THINKING DISTANCE plus the BRAKING DISTANCE.

36
Q

What happens when we double the velocity of the car?

A

The KINETIC ENERGY QUADRUPLES.

37
Q

What momentum do non moving objects have?

A

NO MOMENTUM.

38
Q

What equation do we use to calculate momentum?

A

momentum (kg m/s) = mass (kg) x velocity (m/s)

39
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.

40
Q

What does unifrom mean?

A

When ab object’s speed (velocity) is increasing at a constant rate.

41
Q

Label the following on a distance-time graph: Steady speed, stopped, accelerating and decelerating.

A
42
Q

What does the gradient equal on a distance-time graph?

A

Gradient = speed (The steeper the graph, the faster the object is going.)

This is because: speed = distance / time = (change in vertical axis) / (change in horizontal axis).

43
Q

Label the following on a velocity-time graph: constant acceleration, steady speed, increasing acceleration, steady speed and constant deceleraion.

A
44
Q

What does the gradient equal on a velocity-time graph?

A

Gradient = acceleraion, since acceleration is change in velocity / time.