Forces in Balance

Question 1

Displacement -

Answer 1

Distance without change of direction

Question 2

Vectors -

Answer 2

A physical quantity that has magnitude and direction

Question 3

Scalar Quantity-

Answer 3

A physical quantity that has only magnitude and no direction

Question 4

How to represent a vector quantity?

Answer 4

• represented by an arrow
• direction of arrow shows direction of vector quantity
• length of arrow represents the magnitude of the vector quantity

Question 5

define the term work done

Answer 5

the amount of energy transferred to an object when it is moved by a force

Question 6

equation for work done

Answer 6

work done (J) = Force (N) x Distance (m)

Question 7

examples of vector quantities:

Answer 7

• acceleration
• force
• momentum
• weight
• GPE

Question 8

examples of scalar quantities:

Answer 8

• speed
• distance
• mass
• time

Question 9

why does the change of a shape in a object need more than one force to be applied

Answer 9

Their shape can change by:
- Stretching (forces in opposite directions away from the object)
- Bending (forces that distort the object)
-Compressing (forces in opposite directions towards the object)

Question 10

what does Newtons 3rd law state

Answer 10

when two objects interact with each other, they exert equal and opposite forces on each other

Question 11

example of compression of on object

Answer 11

placing a mass on top of a spring placed on a flat surface:
The two forces are:
1. The weight of the mass
2. The reaction force from the surface to the spring
- These two forces are towards each other

Question 12

example of stretching of on object

Answer 12

mass on the bottom of a vertically hanging spring
The two forces are:
1. The weight of the mass
2. The tension in the spring
These two forces are away from each other

Question 13

example of bending on object

Answer 13

diving board bending when a swimmer stands at the far end
The two forces are:
1. The weight of the swimmer
2. The reaction force from the block to the dividing board

Question 14

equation that thinks force, extension and spring constanct

Answer 14

Force (N) = Extension (m) x Spring Constant (N/m)

Question 15

what is the difference between linear and non-linear relationships

Answer 15

Linear : obey Hooke’s Law and form straight lines
Non-linear : do not obey Hooke’s Law and do not form straight lines when graphed.

Question 16

definition on velocity =

Answer 16

Speed in a particular direction

Question 17

what is Newtons 1st law

Answer 17

states that if the resultant forces zero an object at rest says stationary and a moving object will keep moving at the same speed in the same direction

Question 18

what is Newtons 2nd law of motion:

Answer 18

Acceleration of an object is :
- directly proportional to the resultant force on the object
- Inversely proportional to the mass of the object
acceleration of an object increases if the resultant force on it increases, and decreases if the mass of the object increases.

Question 19

resultant force definition:

Answer 19

the dingle force that has the same effect as all the forces acting on a object

Question 20

what does ‘inertia’ mean

Answer 20

the tendency for the motion of an object to remain unchanged (Newtons 1st law) - unless acted on by resultant force, object either stays stationary or moves at constant speed

Question 21

what is inertial mass

Answer 21

a measure of how difficult it is to change the velocity of an object (Newton 2nd law) - larger masses require larger force to change its velocity

Question 22

what is stopping distance

Answer 22

the minimum distance required to stop a vehicle in a emergency

Question 23

stopping distance =

Answer 23

thinking distance + breaking distance

Question 24

what is thinking distance

Answer 24

distance travelled when reacting

Question 25

what factors will increase thinking distance

Answer 25

• speed
• Alcohol / Drugs
• Distractions - Mobile Phones
• Tiredness

Question 26

what is the braking distance

Answer 26

distance travelled by vehicle whilst the breaking force acts

Question 28

what factors affect the braking distance most;

Answer 28

• icy roads
• worn brakes / tyres
• mass of vehicle
• speed

Question 29

whats the other equation for acceleration

Answer 29

v^2 - u^2 = 2as

Question 30

in this equation what :v^2 - u^2 = 2as what do the letter represent

Answer 30

v = final velocity
u = initial velocity
a = acceleration ( negative if decceleration)
s = distance travelled

Question 31

definition of a moment

Answer 31

the turning effect of a force on an object

Question 32

moment =

Answer 32

Force (N) x Perpendicular distance from line of action to pivot (m)

Question 33

what are moments measured in

Answer 33

Nm (Newton metres)

Question 34

what is the principle of moments?

Answer 34

sum of all clockwise moments about any point = sum of all anti - clockwise moments about any point

Question 35

how can you increase the moment on a leaver:

Answer 35

1. increase size of force
2. increase length of spanner handle

Question 36

how do leavers apply the less force to achieve the same moment

Answer 36

A small force applied at a large distance from a pivot can create a large moment

Question 37

gears turn in ………………… direction

Answer 37

opposite

Question 38

when do you a high gear

Answer 38

• Large gear turns the smaller gear
• smaller gear turns faster than larger gear
• smaller moment - the smaller gear wheel acts close to the pivot
  High gear give high speed but low turning effect

Question 39

what are force multipliers and what do they do

Answer 39

increase size of a force (increasing distance)

Question 40

what is the effect of a low gear

Answer 40

• Smaller gear drives larger gear
• larger gear tuns slower
• turning effect of larger is higher
• low gear gives low speed and a high turning effect

Question 41

if a cyclist is going uphill should they use a high or low gear and why

Answer 41

low gear
- smaller gear drive larger gear
- larger moment - distance from axel is larger in a bigger gear
- force exerted gives a bigger moment –> helping power uphill

Question 42

would you use a high or low gear if you are cycle fast

Answer 42

high gear
- smaller gear has small turning effect but high speed
- turns faster than larger gear