Answer to Question #20313 in Mechanics | Relativity for Muhammad Amir

Question

Train breaks are applied it has covered covered 800 m distance reducing speed from 96km/h to 48km/h before going going to rest how much distance it covered.

Answer 1

From the statement we can get acceleration in time of reducing speed:
v0-at2=v1
v1=at1
at1=48
at2=48
acceleration is constant, therefore: t1=t2
So,
S1=v0t1-at1^2/2
S2=v1t1-at1^2/2
S2=S1-(v0-v1)t1
Now, we have to find t1
t1=48/a
S=v048/a-a48^2/a^2/2
S/48^2=1.5/a
So, 800/1.5*48^2=a
a=4.32
t1=48/4.32
S2=800-48*48/4.32=266.(6) m