forces and motions ✓ Flashcards
(65 cards)
1
Q
what are the SI units for mass ?
A
kilograms
2
Q
what are the SI units for acceleration ?
A
metres per second squared
3
Q
what are the SI units for distance ?
A
metres
4
Q
what are the SI units for force ?
A
newtons
5
Q
what are the SI units for speed ?
A
metres per second
6
Q
what are the SI units for time ?
A
seconds
7
Q
what does stand for t ?
A
time
8
Q
what does stand for m ?
A
mass
9
Q
what does stand for v ?
A
final velocity
10
Q
what does stand for u ?
A
initial velocity
11
Q
what does stand for F ?
A
force
12
Q
what does stand for a ?
A
acceleration
13
Q
what is the equation for speed ?
A
speed = distance ÷ time
14
Q
what is the equation for distance ?
A
distance = speed X time
15
Q
what is the equation for time ?
A
time = distance ÷ speed
16
Q
what is the difference between mass and weight ?
A
mass = the quantity of matter a body contains weight = the force exerted by the gravity on that object
17
Q
what is weight ?
A
a force
18
Q
what is an experiment to show the speed of an object ?
A
- get a toy car
- measure the distance it is going to travel
- time how fast it takes it to move this distance
- use the equation speed = distance ÷ time
19
Q
what is the equation for acceleration ?
A
acceleration = change in speed ÷ time
20
Q
what is the symbol equation for acceleration ?
A
a = v-u ÷ t
21
Q
what is the word equation for final velocity squared ?
A
(final velocity)² = (initial velocity)² + (2 X acceleration X distance)
22
Q
what is a scalar quantity ?
A
has magnitude (size) and direction
23
Q
what is a vector quantity ?
A
has magnitude (size) only
24
Q
what are some examples of scalar quantities ?
A
- power
- distance
- mass
- energy
- speed
- time
25
what are some examples of vector quantities ?
- acceleration
- displacement
- current
- force
- velocity
- momentum
26
what is the difference between velocity and speed ?
velocity is speed with a direction
| speed doesn't have a direction
27
what is the difference between displacement and distance ?
distance is how much ground an object has covered
| displacement is how far out of place an object is
28
what are some different types of force ?
- gravitational force
- upthrust
- air resistance
- friction (drag)
- applied force
29
what can forces do ?
change the speed, shape, or direction of an object
30
what is newtons first law ?
an object remains stationary or at constant velocity unless there is a resultant force on it
31
what is newtons second law ?
- when there is a resultant force on a body it will accelerate
- the larger the mass of the body the less the acceleration
32
what is the equation for weight ?
weight = mass X gravitational force constant
33
how many newtons is the gravitational force constant ?
10 N
34
what is the symbol equation for weight ?
W =mg
35
what do friction and drag do ?
act to oppose the direction of motion
36
what is the equation for force ?
force = mass X acceleration
37
what is F in the equation ?
force
| F is the resultant force
38
how do we work out the velocity on a distance time graph and what is the equation ?
work out the gradient
| rise ÷ run
39
what does stationary look like on a distance time graph ?
a straight line at zero
40
what does constant velocity look like on a distance time graph ?
a straight line
41
what does accelerating look like on a distance time graph ?
steep line moving away from the x axis
42
what does decelerating look like on a distance time graph ?
steep line moving towards the x axis
43
how do we determine the distance travelled on a speed time graph ?
find the area
44
what is earths gravitational field strength ?
10 N/kg
45
what is earth in absence of ?
earth is in absence of drag
46
what do all objects do on earth ?
accelerate towards the earth at the acceleration of free fall which is 10 m/s²
47
as velocity increases what happens to drag ?
drag increases
48
as surface area increases what happens to drag ?
drag increases
49
why do objects falling reach terminal velocity ?
- because as they are falling they are accelerating and then when they reach terminal velocity it is when they cannot accelerate any faster
- the gravitational pull force and the opposing force upthrust or drag are equal in strength
50
what is an experiment to explore the the terminal velocity ?
- parachuter jumps out of plane they will be accelerating
- after 2 minutes parachuter is at his terminal velocity
- parachuter releases his parachute his velocity is decreasing
- after another 2 minutes the parachuter with his parachute open has reached his terminal velocity again but it id slower
51
what is the equation to work out the linear momentum of an object ?
momentum = mass X velocity
52
what is force equal to and what is the equation for this ?
force = change in momentum ÷ time taken = final momentum - initial momentum ÷ time taken
force is equal to rate of change of momentum
53
how do crumple zones, air bags and seat belts save lives ?
they all increase the time taken for the person to stop, if you increase time then the force decreases which reduces chance of injury
54
what is the equation for stopping distance ?
stopping distance = thinking distance + breaking distance
55
what factors affect thinking distance ?
- drinking
- drugs
- disgraced by music
- phones
- tired
56
what factors affect breaking distance ?
- condition of tyres
- mass of vehicle
- wet road
- driving down hill
57
what is an experiment to explore extension varies with force for springs ?
- attach a spring to a clamp
- attach weights onto the spring
- keep putting the weights onto the spring until the spring breaks and cannot hold any more weights
58
what happens on a graph when the weights are put onto a spring elastic band or wires ?
the object at the start becomes elastically deformed and then it passes a point and it becomes plastically deformed
59
what is Hooke's law ?
the extension or compression of an elastic body is directly proportional to the force that causes it
60
where does Hooke's law only apply to ?
it only applies on the linear region on the graph
61
what is the definition of elastic behaviour ?
return to their original length shape when the forces on them are removed
62
what is the meaning of plastic deformation ?
if we go beyond the elastic limit the spring will plastically deform and will be permanently stretched and will not go back to its original shape
63
what is weight ?
a force
64
what is the difference between mass and weight ?
mass is the actual amount of material contained in a body
| weight is the force exerted by the gravity on that object
65
what is an experiment to investigate force on falling objects ?
- parachuter jumps
- at start weight is stronger than air resistance
- further along the fall air resistance becomes equal in strength to weight
