Question

a motorcyclist riding motorcycle a movies travelling at 36 km per hour applies the brakes and stop the motorcycle in 10 seconds another motorcyclist of motorcycle Bihu is travelling at 18 km per hour applies the brakes and storm the motorcycle in 20 seconds plot speed time graph for the two motorcycles which of the two motorcycles Travels father before it come to a stop?​

Answer 1

Given :
Case I:
For motorist A,
Initial Velocity= u=36km/h=36x5/18=10 m/s
Time=t=10s
by using third equation of motion:
V²-u²=2as
0-10x10=2s(V-u)/t
0-10x10=2s(0-10)/10
-2s=-100s
=100/2=50m
Case II:
For motorist B,
Initial velocity=18km/h=18x5/18=5m/s
time=t=20s
By using third equation of motion:
V²-u²=2as
V²-u²=2s(v-u)/t
0-5x5=2s(0-5)/20-25=-s/2s=50m
so both  A and B cover the same distance.
To draw graph ;we need to find acceleration:
For Motorist A:a=(v-u)/t=(0-10)/10=-1 m/s²
For Motorist B:a=(v-u)/t=(0-5)/20=-0.25 m/s²
Time is from 0 to 20 sec and speed is from 5 to 0.25 m/s
Please refer the attachment for the graphs:
Graph 1- Motorist A
Graph 2- Motorist B