Forces, Movement And Shape Flashcards Preview

GCSE Physics*** > Forces, Movement And Shape > Flashcards

Flashcards in Forces, Movement And Shape Deck (49):
1

What does a vector quantity have?

Magnitude and direction

2

What does a scalar quantity have ?

Magnitude only

3

What can scalar quantities never be ?

Negative

4

What can forces do to an object to they way it moves?

• objects can accelerate or decelerate
• objects can change direction

5

What can forces do to objects to change their size ?

• objects can be stretched
• objects can be squeezed

6

What is the normal reaction force ?

When an object rests on a solid if feels a reaction force at 90° to the surface

7

Where does upthrust always occur ?

In a fluid

8

What is thrust ?

Thrust is a reaction force
• it occurs when mass is pushed out the back of something causing the object to move toward
• eg rocket

9

What is an electrostatic force ?

Similar charges repel and opposite charges attract

10

What is an magnetic force ?

Like poles repel, opposite poles attract

11

What always happens to weight ?

Weight is always drawn down from the centre of gravity

12

What is the unit for mass?

Kg

13

What is the unit of weight?

N

14

What depends on the strength of the gravitational field ?

Weight, mass doesn't change

15

What happens to any two objects that have mass?

They will attract each other, the more massive the object the bigger the gravitational force

16

Relation between weight mass and gravitational field strength

Weight = mass x gravitational

17

What is the gravitational field strength on earth?

10 N/kg

18

What is newtons second law?

In the presence of a resultant force a body experiences an acceleration

19

What does resultant mean ?

Overall

20

What overall force does a stationary object have?

No overall force

21

What is the equation linking acceleration, force and mass ?


Acceleration = force/mass

22

If acceleration is equal to force, what is mass?

Constant mass

23

What is force proportional to ?

Acceleration and acceleration is proportional to force

24

Describe terminal velocity

• when object starts falling it is accelerating as weight is much greater than air resistance
• The forces start to balance out however still accelerating but not as quickly
• when weight is equal to air resistance the object stops accelerating and falls at a constant speed, this is called terminal velocity

25

What is stopping distance made up of?

• thinking distance
• braking distance

26

What is thinking distance?

It is the distance travelled whilst the body is reacting to the message it receives from the brain

27

What is braking distance?

It is the distance travelled whilst the car is decelerating to a stop

28

How does the thinking distance increase?

It increases linearly

29

How does braking distance increases?

It increases exponentially

30

What does braking distance depend on?

Speed squared

31

What affects braking distance?

• vehicle condition - brake pads/tyres are worn, braking will take longer
• road condition - rain or ice on the road surface will increase braking distance
• mass of car - heavier car=take longer to stop
( only use if others can't be used )

32

What affects thinking distance ?

• age
• drugs/alcohol
• fatigue
• distraction
- they all increase reaction time

33

What is the moment of a force?

It Is a measure of the forces turning effect

34

What will forces with a big moment have ?

Larger turning effect

35

What an two identical forces have?

They can have entirely different moments

36

What is the equation linking force, moment and perpendicular distance from pivot ?


Moment = force x distance

37

What is the principle of moment ?

In equilibrium moments anticlockwise equals moments clockwise

38

What is the equation linking 2 forces and 2 perpendicular distances ?

F1d1 = F2d2

39

What is the centre of mass ?

It is an imaginary point through which all the mass of an object can be said to act

40

What will an object do around the centre of mass ?

Rotate

41

what will cause a object to fall over?

When an object's centre of mass falls outside its base the object will topple over

42

What is hooks law?

That the extension of a spring is proportional to the load

43

What also about hooks law but only at the beginning?

A wire and rubber band

44

What equation links force, spring constant and extension ?


Force=spring constant x extension

45

What is the spring constant measured in ?

Newtons per metre (N/m)

46

What is the spring constant ?

The "stiffness" of a spring

47

What does a large spring constant indicate and what does a small spring constant indicate ?

• Large spring constant = very stiff spring
• small spring constant = very loose spring

48

What happens when you stretch a spring to its elastic limit ?

It won't go back to its original shape

49

What is elastic behaviour ?

When you stretch and object with this behaviour it will return to its original shape