Answer:
[tex]2.5\ m/s^2[/tex]
Step-by-step explanation:
Newton's Second Law: Force on a body is equal to the product of mass and acceleration of the centre of the mass of the body.
[tex]Force(F)=Mass(m)\times Acceleration(a)[/tex]
Initially:
[tex]Let\ mass=m\ kg\\\\acceleration=10\ m/s^2\\\\Force(F)=m\times 10=10m[/tex]
At the end of the road:
[tex]Let\ mass=4\times m\ kg\\\\acceleration=a\ m/s^2\\\\Force(F)=4m\times a=4ma[/tex]
[tex]Both\ forces\ are\ equal\\\\4ma=10m\\\\divide\ both\ the\ sides\ by\ m\\\\4a=10\\\\a=\frac{10}{4}\\\\a=2.5\ m/s^2[/tex]