stopping distance
Stopping Distance and
Reaction Time
20 m s
-1
A
B
O
positive direction
40 m
The driver in the car B sees the man A 40 m away at time t = 0.
The velocity of the car changes according to the graph below.
V / m s-1
40
30
20
10
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
t/s
V / m s-1
40
30
20
10
0
0.5
1.0
1.5
2.0
2.5
3.0
Will the car B collide with the man A ?
3.5
4.0
4.5
5.0
5.5
t/s
V / m s-1
40
Area = 10 m. It is the distance travelled by the car when the driver is thinking.
This is known as thinking distance.
30
20
10
0
0.5
1.0
1.5
Reaction Time =0.5 s
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
From t = 0 s to t = 0.5 s , the driver is thinking what to do. He does not apply the brakes during this period.
t/s
V / m s-1
40
Area = 10 m. It is the distance travelled by the car when the driver is thinking.
This is known as thinking distance.
30
20
10
0
0.5
1.0
1.5
2.0
2.5
20 m s-1
3.0
3.5
4.0
4.5
5.0
5.5
t/s
A
B
O
positive direction
10 m
40 m
V / m s-1
40
30
Area = 25 m. It is the distance travelled by the car during braking. This is known as braking distance.
20
10
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
Braking Time = 2.5 s
From t = 0.5 s to t = 3 s ,the brakes are applied.
The car slows down until it stops at t = 3 s.
5.5
t/s
V / m s-1
40
30
Area = 25 m. It is the distance travelled by the car during braking. This is known as braking distance.
20
10
0
0.5
1.0
1.5
2.0
2.5
3.0
Braking Time = 2.5 s
3.5
4.0
stop
O
4.5
B
5.0
5.5
t/s
A positive direction
10 m
25 m
40 m
stop
B
O
A positive direction
10 m
25 m
40 m
Stopping Distance = Thinking Distance + Braking Distance
= 10 m + 25 m
Reaction Time
20 m s
-1
A
B
O
positive direction
40 m
The driver in the car B sees the man A 40 m away at time t = 0.
The velocity of the car changes according to the graph below.
V / m s-1
40
30
20
10
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
t/s
V / m s-1
40
30
20
10
0
0.5
1.0
1.5
2.0
2.5
3.0
Will the car B collide with the man A ?
3.5
4.0
4.5
5.0
5.5
t/s
V / m s-1
40
Area = 10 m. It is the distance travelled by the car when the driver is thinking.
This is known as thinking distance.
30
20
10
0
0.5
1.0
1.5
Reaction Time =0.5 s
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
From t = 0 s to t = 0.5 s , the driver is thinking what to do. He does not apply the brakes during this period.
t/s
V / m s-1
40
Area = 10 m. It is the distance travelled by the car when the driver is thinking.
This is known as thinking distance.
30
20
10
0
0.5
1.0
1.5
2.0
2.5
20 m s-1
3.0
3.5
4.0
4.5
5.0
5.5
t/s
A
B
O
positive direction
10 m
40 m
V / m s-1
40
30
Area = 25 m. It is the distance travelled by the car during braking. This is known as braking distance.
20
10
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
Braking Time = 2.5 s
From t = 0.5 s to t = 3 s ,the brakes are applied.
The car slows down until it stops at t = 3 s.
5.5
t/s
V / m s-1
40
30
Area = 25 m. It is the distance travelled by the car during braking. This is known as braking distance.
20
10
0
0.5
1.0
1.5
2.0
2.5
3.0
Braking Time = 2.5 s
3.5
4.0
stop
O
4.5
B
5.0
5.5
t/s
A positive direction
10 m
25 m
40 m
stop
B
O
A positive direction
10 m
25 m
40 m
Stopping Distance = Thinking Distance + Braking Distance
= 10 m + 25 m