Physics 2019 Yr 11

Question 1

Distance

Answer 1

The distance between 2 points is how far they are apart

Question 2

Displacement

Answer 2

Is the distance between 2 points in a specified direction

Question 3

Speed

Answer 3

Is the rate at which distance changes with time
Speed = d/t
Av speed = tot distance/ tot time taken

Question 4

Velocity

Answer 4

Is the rate of change of displacement with time
Velocity = displacement/ time unit m/s
Av velocity = (initial speed + final speed) / 2

Question 5

Average speed

Answer 5

Is the total distance travelled divided by the total time taken
Av speed = tot distance/ tot time

Question 6

Average velocity

Answer 6

Initial speed+ final speed / 2

Question 7

Acceleration

Answer 7

Is the rate of change of velocity with time

A= change in velocity/time taken

Question 8

Average speed

Answer 8

Is the total distance travelled divided by the total time taken
Av speed = tot distance/ tot time

Question 9

Scalar

Answer 9

Is a physical quantity that has a magnitude but not direction
Eg distance, speed, rate of change of speed and time

Question 10

Vector

Answer 10

Is a physical quantity that has both magnitude and direction
Eg displacement, velocity, acceleration and force

Question 11

Balanced forces

Answer 11

When the forces exerted on an object are of equal size but acting in different (opposite) directions, then the forces are known as -balanced forces-

Question 12

Unbalanced forces

Answer 12

When the forces applied to an object are unequal in size then the forces are known as -unbalanced forces-

Question 13

Force measured in ?

Answer 13

Neutons

Question 14

Springs

Answer 14

When a force is applied to a spring e.g hanging slotted masses on it, the spring will stretch. We usually call the amount it has stretched the EXTENSION. The relationship between the force applied to the spring and the extension is given by HOOKES LAW

Question 15

Spring hookes law

Answer 15

Up to the limit of proportionality the extension of a helical spring is directly proportional to the applied load
Law is only true if the spring is not stretched beyond the LIMIT OF PROPORTIONALITY
A spring stretched beyond is ELASTIC LIMIT will not return to its original length and it has been permanently stretched

Question 16

F=ke

Answer 16

Force = force 
K = spring constant 
E = extension

Question 17

Force extension graph

Answer 17

The gradient of a force extension graph is equivalent to the print constant

Question 18

Another useful way of writing hookes law

Answer 18

F1 over F2

E1 over E2

Question 19

Turning effect or moment of a force

Answer 19

Turning effect of a force is called the moment and the point at which the object is fixed is called the moment. The size of the turning effect or moment depends of the size of the force and the distance between the force and the pivot

Question 20

Principle of moments (law of the lever)

Answer 20

The principle of moments tells us about what happens when a lever with several forces acting on it is balanced or in equilibrium

Question 21

Moment =

Answer 21

M = force x distance (perpendicular distance form pivot)

Question 22

Reaction force

Answer 22

The reaction force acts through the pivot and does not create a Turing effect
Reaction force at pivot = acm force + cm force

Question 23

Conditions for equilibrium

Answer 23

Clockwise moment about pivot = anti-clockwise moment about pivot
There must be no resultant or unbalanced force in any direction

Question 24

Levers

Answer 24

Effort = (input) force
Load = (output) force 
Furst class 
Scissors 
Seesaw 
Second class 
Nut cracker 
Wheel barrow 
Third class 
Tweezers 
Fishing rod

Question 25

Centre of gravity

Answer 25

All points of an object are pulled toward the centre of gravity. It is a reg shale such as a rectangular block the centre of gravity will be at the very centre of the object.

Question 26

Centre of mass

Answer 26

The centre of mass of an object is the point where its total mass appears to act. Unless an object is very large the centre of mass and the centre of gravity will be at the same point

Question 27

How to find the c of g of a lever

Answer 27

The centre of gravity of a metre ruler is located at its midpoint 50cm u can also use this to work out the weight of the ruler without weighing it Hand ruler on retort stand, make the pivot anywhere except the 59cm mark and hang 2N on the shorter side. Move until the metre stick is in equilibrium (balanced). The moment produced by the 2N is now the same as the moment produced by the weight of the stick actingat the 50cm mark

Question 28

What factors affect the stability of an object

Answer 28

The position of the centre of gravity of an object affects whether or not it will topple easily The weight of an object acts vertically downwards from its centre of gravity. The object will topple when the line of action of this force (the weight) falls outside its base or to the outside of the toppling edge. If the line of action of the force falls inside the base then the object will be stable and returns to its original position. The stability can therefore be increased by lowering the centre of gravity of an object Widening the base

Question 29

Pressure

Answer 29

Pressure is the force exerted per m squared The amount of pressure depends on the size of the force and on the area over which the force acts. The smaller the area the greater the pressure. And the other way round

Question 30

We can define pressure as

Answer 30

Force applied per unit surface area Newton’s per metre squared (N/ m2(squared)) The unit of pressure is the pascal 1Pa= 1N/msquared

Question 31

Equation for pressure

Answer 31

``` P = F / A F = P x A A = F/P ```

Question 32

What is the area under a speed time graph

Answer 32

The distance travelled