EX unit one: forces and motion

Question 1

distance travelled =

Answer 1

speed x time

Question 2

unit of speed

Answer 2

metres/second or kilometres/hour

Question 3

on a distance time graph what does the gradient or slope give?

Answer 3

the speed

Question 4

on a distance time graph what does a horizontal line mean?

Answer 4

the object is stationary

Question 5

acceleration =

Answer 5

change in velocity / time taken

Question 6

what is the symbol for acceleration

Answer 6

a

Question 7

what is the symbol for time

Answer 7

t

Question 8

what is the symbol for velocity or speed

Answer 8

v

Question 9

what is the symbol for distance

Answer 9

x or s

Question 10

in a velocity time graph, what does the gradient or slope give?

Answer 10

acceleration

Question 11

in a velocity time graph, what does the straight line mean?

Answer 11

constant acceleration

Question 12

in a velocity time graph, what does the area under the graph show?

Answer 12

distance

Question 13

final velocity squared =

Answer 13

initial velocity squared x 2 x acceleration x distance moved

Question 14

what is the symbol for final velocity

Answer 14

v

Question 15

what is the symbol for initial velocity

Answer 15

u

Question 16

what are forces

Answer 16

pushes or pulls that one body exerts on another

Question 17

normal reaction

Answer 17

the special name for the contact force that acts on an object pressing down on another object.

Question 18

tension

Answer 18

in strings, cables, ropes etc. things that are being stretched.

Question 19

friction

Answer 19

the force that opposes motion, either when you try to make something move or whilst it is moving

Question 20

air resistance

Answer 20

friction between an object and the air (or gas) that its moving through

Question 21

viscous drag

Answer 21

similar to air resistance, but occurs when an object is moving through a liquid.

Question 22

upthrust

Answer 22

the upward force that liquids and gases exert on objects.

Question 23

weight

Answer 23

the force that acts on a body because of gravity

Question 24

magnetic

Answer 24

forces that magnets exert on other magnets or things made of iron

Question 25

electrostatic

Answer 25

the force between electrically charged objects

Question 26

unit of force

Answer 26

newtons (N)

Question 27

are forces vector or scalar

Answer 27

vector

Question 28

unbalanced forces acting on an object will cause...

Answer 28

a change in that object | e.g. accelerate, decelerate, change direction or change shape

Question 29

how do you work out resultant force

Answer 29

subtract the forces acting on the object, and write the answer before the direction

Question 30

hooke's law

Answer 30

the extension of a spring is directly proportional to the force pulling it.

Question 31

glass does not stretch but breaks. this means it is...

Answer 31

brittle

Question 32

plasticine does stretch but does not return to its original shape. this means it is...

Answer 32

plastic

Question 33

steel does stretch and does return to its original shape. this means it is...

Answer 33

elastic

Question 34

what is the elastic limit

Answer 34

the point where the spring is overstretched and it will not return to its original length when the force is removed.

Question 35

do rubber bands obey hookes law?

Answer 35

no, if you continue to stretch it the band will break.

Question 36

force =

Answer 36

mass x acceleration

Question 37

what does newton's second law show?

Answer 37

the acceleration of an object is proportional to the force acting on it

Question 38

to decrease the time and distance it takes for a car to stop by breaking, what must you increase

Answer 38

the friction force between the tyres and road surface (as shown through a = f / m , and how you cannot change the mass)

Question 39

thinking distance

Answer 39

the distance you travel before you start to apply the brakes, which in turn, depends on your reaction time.

Question 40

braking distance

Answer 40

the distance you travel while the car is decelerating to rest.

Question 41

give thinking distance factors

Answer 41

alcohol and drugs, tiredness, visibility, distractions

Question 42

give braking distance factors

Answer 42

worn tyres and brakes, icy and wet roads, speed

Question 43

what is the approximate value for the gravitational field strength on earth

Answer 43

10 m/s squared

Question 44

weight =

Answer 44

mass x gravitational field strength

Question 45

what is the symbol for weight

Answer 45

W

Question 46

what is the symbol for mass

Answer 46

m

Question 47

what is the symbol for gravitational field strength

Answer 47

g

Question 48

explain terminal velocity

Answer 48

when the size of the drag force caused by air resistance increases with speed - at some speed the size of the drag foce will be enough to balance the weight of the object. so the overall resuktant force on the object will be zero and it will no longer accelerates having reached its terminal/maximum velocity.

Question 49

is acceleration a vector or scalar quantity

Answer 49

vector

Question 50

are accelerating objects changing their velocity or their speed

Answer 50

they must be changing both

Question 51

momentum

Answer 51

a measure of how easily an object can be brought to rest

Question 52

is momentum a vector or scalar quantity

Answer 52

vector

Question 53

what is momentum measured in

Answer 53

kilogram metres per second | kg m/s

Question 54

what is mass measured in

Answer 54

g or kg

Question 55

what is an elastic collision

Answer 55

one where no energy is lost

Question 56

conservation of momentum is

Answer 56

the momentum of bodies colliding is always conserved.

Question 57

total momentum of the two bodies before collision =

Answer 57

total momentum of the two bodies after collision

Question 58

if one object is moving north and the other is moving south, what must you remember?

Answer 58

that the sign of one must be negative. it is up to you to choose whether to make north or south positive but you must stick to it.

Question 59

force =

Answer 59

change in momentum / time taken

Question 60

change in momentum is

Answer 60

final momentum - initial momentum

Question 61

what is the symbol for momentum

Answer 61

p

Question 62

what is the symbol for force

Answer 62

F

Question 63

what are crumple zones

Answer 63

cars are designed with crumple zones to increase deceleration times, decrease forces and reduce injuries

Question 64

what is newtons third law

Answer 64

for every action there is an equal and opposite reaction.

Question 65

key features of every action-reaction pair of forces (involving newtons third law)

Answer 65

they are equal in size, opposite in direction, of the same type, and act on different objects

Question 66

moment =

Answer 66

force x perpendicular distance from pivot

Question 67

what is the moment of a force

Answer 67

it's 'turning effect'. levers are used to increase the turning effect of a force by increasing the distance between the force applied and the point around which the object will turn.

Question 68

sum of clockwise moments =

Answer 68

sum of anticlockwise moments

Question 69

if a beam is stationary, two conditions must be fulfilled:

Answer 69

the sum of the upward forces acting on the beam is equal to the sum of the downward acting forces. the sum of clockwise moments acting on the beam about any point is equal to the sum of anticlockwise moments acting on the beam.

Question 70

what is the centre of gravity

Answer 70

the whole weight of an object acts through one point of the object called its centre of gravity.