Topic 2 Flashcards
Done except 2.31
2.1/2.3
What is a scalar quantity?
-Has magnitude
-No direction
2.2/2.3
What is a vector quantity?
-Has magnitude
-Has direction
2.4
State 6 examples of vector quantities
-Displacement
-Velocity
-Acceleration
-Force
-Weight
-Momentum
2.4
State 4 examples of scalar quantities
-Distance
-Speed
-Mass
-Energy
2.5
Define the term velocity
Speed in a stated direction
2.6
State the equation for speed
s=d/t
(Average) speed (m/s) = distance (m) ÷ time (s)
2.8
State the short equation for acceleration
-a=v-u/t
-Units in order: m/s², m/s, s
2.8
Rearrange the short acceleration equation for time
t=v-u/a
2.8
Rearrange the short acceleration equation for final velocity
v=u+at
2.8
Rearrange the short acceleration equation for initial velocity
u=v-at
2.9
State the long equation for acceleration
v²-u²=2ax
Final velocity² (m/s) - initial velocity² (m/s) = 2 × acceleration (m/s²) × distance (m)
2.9
Rearrange the long equation for acceleration to make acceleration the subject
a=v²-u²/2x
2.9
Rearrange the long equation for acceleration to make distance the subject
x=v²-u²/2a
2.9
Rearrange the long equation for acceleration to make initial velocity the subject
u=√v²-2ax
2.9
Rearrange the long equation for acceleration to make final velocity the subject
v=√2ax+u²
2.11
Describe a range of laboratory methods for determining the speed of an object
-2 light gates -> measure time (1st gate starts timer, 2nd stops it)
-1 light gate (time how long beam of light blocked & d given by length of flag passing thru gate)
-Metre ruler stick/measuring tape + stop clock
2.12
What is the typical walking speed?
1.5 m/s
2.12
What is the typical running speed?
3 m/s
2.12
What is the typical speed for cycling?
6 m/s
2.12
What is the typical speed for sound?
330 m/s
2.12
What is the typical speed for wind?
10-20 km/h
2.12
What is the typical speed for transportation systems?
20-50 m/s
2.13
What is the earth’s gravitational field strength?
10 N/kg
2.14
Describe Newton’s first law of motion
-Object remains stationary/constant velocity if F = BALANCED/no resultant F acting
-If resultant F acts object accelerates
2.15
Describe Newton’s second law of motion. What equation comes with it? (Include units)
-a (of object) ∝ resultant F (acting on it)
-a inversely ∝ to m (of object)
-F=ma
Units in order: N, kg, m/s²
2.16
Define the term weight
F due to pull of gravity of an object
2.16
State the equation for weight. Include units
W=mg
Units in order: N, kg, N/kg
2.17
What piece of specialised equipment can you use to measure weight
Newton metre
2.18
Describe the relationship between the weight of a body and the gravitational field strength
Directly proportional
2.19
Devise an experiment to investigate the effect of mass on acceleration
-Variables
I=Mass
D=Acceleration
C=Force
-Prop up 1 end of ramp
-Card on top of trolley (record l)
-Attach string to trolley & pass over pulley at end of ramp
-2 light gates (top & bottom) & m on end of string (this m = constant through out)
-Release
-Data logger records s as passes through each light gate
-Record t to get from 1 light gate to other
-Repeat for diff masses (that you change on top of trolley)
2.20H 2.21H
Describe circular motion
-Everywhere speed = constant
-Everywhere velocity = changing
-So must be acceleration
-So must be resultant force:
Centripetal force
-Acting towards centre of circle
2.22H
What is inertia
Tendency of object to continue in current state (rest/uniform velocity)
2.23H
Describe Newton’s third law of motion
When 2 objects interact, the forces they exert on each other are equal and opposite
2.23H
Describe Newton’s third law in the equilibrium situation of a cat sitting on the ground
-Cat pulls Earth up
-Earth pulls cat down
-F = equal in size
-Opposite in direc
2.23H
Trolley question:
https://www.bbc.co.uk/bitesize/guides/zg9smsg/revision/2
https://www.bbc.co.uk/bitesize/guides/zg9smsg/revision/2
2.23H
Cannon question:
https://www.bbc.co.uk/bitesize/guides/zg9smsg/revision/2
https://www.bbc.co.uk/bitesize/guides/zg9smsg/revision/2
2.24H
Define the term momentum
-Product of mass and velocity
-Vector quantity
2.24H
State the equation for momentum. Include units
P=mv
Units in order: kg m/s, kg, m/s
Describe the law of conservation of momentum
Momentum is the same before and after a collision
2.26H
State the long equation for force. Include units
Force=final momentum-initial momentum/time
F=mv-mu/t
Units in order: N, kg m/s, kg m/s, s
2.27
What is a typical reaction time?
0.2-0.9 seconds
2.27
Describe the ruler drop test used to measure human reaction time.
-Line up 0 with person’s hand
-Drop ruler
-Measure d by seeing where caught ruler
-Longer d = longer reaction t
2.27
State 2 weaknesses of the ruler drop test
-Person may be distracted
-Not accurate -> improve by multiple readings & more intervals on ruler
2.28
What is thinking distance?
d car travels before react to stimulus
2.28
What is braking distance?
d car travels with brakes applied
2.28
State the equation for stopping distance
Stopping distance= Thinking distance + Braking Distance
2.29
What factors affect braking distance (and therefore stopping distance)
-Mass
-Speed
-Conditions of brakes/tyres
-Friction
-State of road
2.30
What factors affect the driver’s reaction time?
-Drugs
-Distractions
-Alcohol
-Tiredness
Age
Illness
Describe the relationship between force and time
Inversely proportional
Explain how crumple zones decrease injuries
-Absorbs some F from impact
-↑ t taken for collision
-↓ r. of change of P of driver
-↓ F -> ↓ injuries
Explain how seat belts decrease injuries
-Stretch ↑ t taken for collision
-↓ r. of change of P
-↓ F of impact -> ↓ injuries
Explain how airbags decrease injuries
-Cushion driver
-↑ t taken for collision
-↓ r. of change of P
-↓ F of impact -> ↓ injuries
2.32
Describe how the stopping distance of an object is affected by speed
Faster speed = longer stopping d
2.33P
State the equation for work done (energy). State units
Work done = force × distance
Units in order: J, N, m
2.33P
What equation can you equate the work done equation to?
KE=1/2mv²
Ans: 1/2mv² = f×d
