Unit 11 - Forensic Traffic Collision Investigation
B - Explore how science is used in road traffic collision investigation
Road traffic scenario’s calculations:
Given equations:
● V = u + at
1 2
● S = ut + 2
𝑎𝑡
2 2
● 𝑉 = 𝑢 + 2as
𝑑
● Velocity: v = 𝑡
● Coefficient of friction: F = µ𝑅
Collision Scenario 1:
Car A -
Mass = 3000 kg
Initial velocity = 50 mph (22.3 m/s)
Travelled 76 metres in 7 seconds before colliding with Car B.
Car B -
Mass = 2700 kg
Velocity = 40 mph (17.88 m/s)
−1
Average velocity of Car A = = 10.857 𝑚𝑠
𝑣−𝑢 10.857 − 22.3 2
Acceleration of Car A = 𝑡
= 7
= -1.635𝑚/𝑠
Coefficient of friction of Car A:
Car A moves at: 3000 x 1.635 = 4905 N
The mass of gravity = weight x friction of gravity
So, 3000 x 9.8 = 29400 kg
𝑓𝑜𝑟𝑐𝑒
Kinetic coefficient of friction = 𝑚𝑎𝑠𝑠 𝑜𝑓 𝑔𝑟𝑎𝑣𝑖𝑡𝑦
4905
So, 29400
= 0.167
Coefficient of friction of Car B:
Car B moves at: 2700 x 0 = 0 N
The mass of gravity = weight x friction of gravity
So, 2700 x 9.8 = 26460 kg
𝑓𝑜𝑟𝑐𝑒
Kinetic coefficient of friction = 𝑚𝑎𝑠𝑠 𝑜𝑓 𝑔𝑟𝑎𝑣𝑖𝑡𝑦
0
So, 26460
=0
, Collision Scenario 2:
Car A -
Mass = 2900 kg
Initial velocity = 60 mph (26.82 m/s)
Travelled 86 minutes & 8 seconds before colliding with Car B
Car B -
Mass = 2750 kg
Velocity = 70 mph (31.29 m/s)
−1
Average velocity of Car A = = 10.75 𝑚𝑠
𝑣−𝑢 10.75 − 26.82
Acceleration of Car A = 𝑡
= 8
= -2.00875
Coefficient of friction of Car A:
Car A is moving at: 2900 x 2.00875 = 5825.375 N
The mass of gravity = weight x friction of gravity
So, 2900 x 9.8 = 28420 kg
𝑓𝑜𝑟𝑐𝑒
Kinetic coefficient of friction = 𝑚𝑎𝑠𝑠 𝑜𝑓 𝑔𝑟𝑎𝑣𝑖𝑡𝑦
5825.375
So, 28420
= 0.205
Coefficient of friction of Car B:
Car B is moving at: 2750 x 0 = 0 N
The mass of gravity = weight x friction of gravity
So, 2750 x 9.8 = 26950 kg
𝑓𝑜𝑟𝑐𝑒
Kinetic coefficient of friction = 𝑚𝑎𝑠𝑠 𝑜𝑓 𝑔𝑟𝑎𝑣𝑖𝑡𝑦
0
So, 26950
=0
Collision Scenario 3:
Car A -
Mass = 2900 kg
Initial velocity = 80 mph (35.76 m/s)
Car A travelled 86 minutes in 9 seconds before colliding with Car B
Car B -
Mass = 2750 kg
Initial velocity = 70 mph (31.29 m/s)
−1
Average velocity of Car A = = 9.56 𝑚𝑠
B - Explore how science is used in road traffic collision investigation
Road traffic scenario’s calculations:
Given equations:
● V = u + at
1 2
● S = ut + 2
𝑎𝑡
2 2
● 𝑉 = 𝑢 + 2as
𝑑
● Velocity: v = 𝑡
● Coefficient of friction: F = µ𝑅
Collision Scenario 1:
Car A -
Mass = 3000 kg
Initial velocity = 50 mph (22.3 m/s)
Travelled 76 metres in 7 seconds before colliding with Car B.
Car B -
Mass = 2700 kg
Velocity = 40 mph (17.88 m/s)
−1
Average velocity of Car A = = 10.857 𝑚𝑠
𝑣−𝑢 10.857 − 22.3 2
Acceleration of Car A = 𝑡
= 7
= -1.635𝑚/𝑠
Coefficient of friction of Car A:
Car A moves at: 3000 x 1.635 = 4905 N
The mass of gravity = weight x friction of gravity
So, 3000 x 9.8 = 29400 kg
𝑓𝑜𝑟𝑐𝑒
Kinetic coefficient of friction = 𝑚𝑎𝑠𝑠 𝑜𝑓 𝑔𝑟𝑎𝑣𝑖𝑡𝑦
4905
So, 29400
= 0.167
Coefficient of friction of Car B:
Car B moves at: 2700 x 0 = 0 N
The mass of gravity = weight x friction of gravity
So, 2700 x 9.8 = 26460 kg
𝑓𝑜𝑟𝑐𝑒
Kinetic coefficient of friction = 𝑚𝑎𝑠𝑠 𝑜𝑓 𝑔𝑟𝑎𝑣𝑖𝑡𝑦
0
So, 26460
=0
, Collision Scenario 2:
Car A -
Mass = 2900 kg
Initial velocity = 60 mph (26.82 m/s)
Travelled 86 minutes & 8 seconds before colliding with Car B
Car B -
Mass = 2750 kg
Velocity = 70 mph (31.29 m/s)
−1
Average velocity of Car A = = 10.75 𝑚𝑠
𝑣−𝑢 10.75 − 26.82
Acceleration of Car A = 𝑡
= 8
= -2.00875
Coefficient of friction of Car A:
Car A is moving at: 2900 x 2.00875 = 5825.375 N
The mass of gravity = weight x friction of gravity
So, 2900 x 9.8 = 28420 kg
𝑓𝑜𝑟𝑐𝑒
Kinetic coefficient of friction = 𝑚𝑎𝑠𝑠 𝑜𝑓 𝑔𝑟𝑎𝑣𝑖𝑡𝑦
5825.375
So, 28420
= 0.205
Coefficient of friction of Car B:
Car B is moving at: 2750 x 0 = 0 N
The mass of gravity = weight x friction of gravity
So, 2750 x 9.8 = 26950 kg
𝑓𝑜𝑟𝑐𝑒
Kinetic coefficient of friction = 𝑚𝑎𝑠𝑠 𝑜𝑓 𝑔𝑟𝑎𝑣𝑖𝑡𝑦
0
So, 26950
=0
Collision Scenario 3:
Car A -
Mass = 2900 kg
Initial velocity = 80 mph (35.76 m/s)
Car A travelled 86 minutes in 9 seconds before colliding with Car B
Car B -
Mass = 2750 kg
Initial velocity = 70 mph (31.29 m/s)
−1
Average velocity of Car A = = 9.56 𝑚𝑠
