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Additional Physics From Hell > Forces > Flashcards

Flashcards in Forces Deck (52):
1

What is happening if the resultant force is 0 on a stationary object

It stays stationary

2

What is the resultant force

The sum of the forces

3

What happens to a moving object if the resultant force is 0?

It keeps moving at a constant speed

4

What happens when the forces aren't balanced in a stationary object

It begins to move in the direction of the resultant force

5

What happens to a moving object when the resultant force isn't 0

It accelerates or slows down depending on the direction of the resultant force

6

What does acceleration depend on?

Size of the force
The mass

7

What is acceleration measured in?

M/s2

8

What is velocity measured in?

M/s

9

How do you find the distance travelled in a velocity time graph

The area under the graph is the total distance travelled

10

What is Newton's first law?

Object stays still unless acted on by unbalanced forces

11

What is Newton's third law?

If a body exerts a force on another, there is an equal and opposite force

12

What is force measured in?

N Newton's

13

When there is a horizontal line on a velocity time graph, what does that mean?

Object is moving at a constant speed

14

When there is a horizontal line on a distance time graph, what does that mean?

Object is stationary

15

When there is a straight diagonal line going up on a distance time graph, what does that mean?

Object is moving at a steady speed (constant speed)

16

When there is a straight diagonal line going up on a velocity time graph, what does that mean?

Object is moving at a constant acceleration

17

When there is a curved line going up on a distance time graph what does that mean?

Object is accelerating

18

When there is a curved line going down in a distance time graph what does that mean?

Object is decelerating

19

When there is a curved line going up on a velocity time graph, what does that mean?

Increased rate of acceleration

20

When there is a curved line on a velocity time graph going down, what does that mean?

Increased rate of deceleration

21

When there is a diagonal line going down on a velocity time graph what does that mean?

Constant deceleration of object

22

When there is a diagonal line going down on a distance time graph, what does that mean?

Object is travelling at a steady speed (constant speed) back to the start

23

The steeper the Line...

The greater the acceleration

24

How do you calculate the gradient?

Rise/run

25

What does working out the gradient represent on a velocity time graph

The acceleration

26

What does the stopping distance of a car depend on ?

Thinking distance and braking distance

27

What 5 forces act on a car moving at a steady speed?

Weight
Reaction force
Driving force
Friction
Air resistance

28

Which force on a car is pointed down?

Weight (gravity)

29

Which force on a car is pointing up?

Reaction force

30

Which forces on a car are indirectly proportional?

Weight(gravity) and reaction force

Driving force and air resistance

31

Format in drawing resultant force?

E.g.

2N^
3N>

32

If the driving force is bigger than the air resistance of a car moving, what is the car doing ?

Accelerating

33

For a car to slow down, what has to happen (2)

The driving force must be reduced

The resistive forces must be increased

34

How do you work out stopping distance?

Stopping distance= thinking distance+breaking distance

35

What is thinking distance?

Distance travelling between need for breaking and brakes being pressed

36

What is breaking distance ?

Distance taken to stop after brakes have been applied

37

What 3 factors affect thinking distance?

Tired
Distracted
Influence from drugs and alcohol

38

What 2 factors affect breaking distance?

The cars tyres or brakes are in poor condition

Weather conditions I.e. Icy roads

39

What happens when the braking distance increases?

Car's speed increases

40

What happens when brakes are applied to a car? (3)

Work is done by the friction force

Kinetic energy of the vehicle is reduced because the speed decreases

Increases temperature of the brakes

41

What is terminal velocity ?

When the resultant force is 0

42

What are the main 2 forces exerted on falling objects ?

Weight(gravity)

Air resistance

43

What are the 3 stages of falling (3)

Since in1) object accelerates downwards
No air resistance

2) air resistance increases and becomes bigger than the weight/ force

3) the object's weight and air resistance is balanced. It reaches a steady speed called terminal velocity

44

Why does a coin fall faster than a feather ?

The feather is lighter so air resistance increases quickly and it falls at terminal velocity

The coin is heavier so it travels fast before air resistance is large enough to balance the weight. So, it probably hits the ground before terminal velocity

45

On the moon, what happens when you drop a light object and a heavy object and why?

They land at the same time.

The moons gravity is too weak so there is no air resistance. Therefore, the objects had the same acceleration

46

On a velocity time graph for falling objects, when a line is horizontal, what does it mean?

Object has reached terminal velocity

47

What are the 3 stages of dropping something?

1) object accelerates because the force of gravity is bigger than friction force

2) it is still accelerating but acceleration decreases as friction is increasing

3) it stops accelerating and reaches terminal velocity

48

What is the difference between weight and mass ?

Weight is the result of gravity and is the force acting on mass. measures in N

Mass is how much stuff is in an object measure in kg

49

What do elastic objects do?

Store elastic potential energy when stretched

50

What is the relationship between the extension of an elastic object and the force applied?

They are directly proportional

51

What is the spring constant measured in?

N/m

52

The greater the spring constant...

The greater the value of K so the stiffer the spring