If a body starts from rest and travels 120 m in the 8th second, the acceleration is :

To solve this problem, we need to use the equation of motion that relates distance, acceleration, and time. The equation is:

s = ut + 0.5at^2

where: s = distance travelled u = initial velocity t = time a = acceleration

In this case, the body starts from rest, so the initial velocity (u) is 0. The distance travelled (s) in the 8th second would be the total distance travelled in 8 seconds minus the total distance travelled in 7 seconds.

So, we need to set up two equations, one for t = 8 seconds and one for t = 7 seconds, and then subtract the second from the first to find the distance travelled in the 8th second.

For t = 8 seconds: s1 = 08 + 0.5a*8^2 = 4a

For t = 7 seconds: s2 = 07 + 0.5a*7^2 = 3.5a

The distance travelled in the 8th second is therefore s1 - s2 = 4a - 3.5a = 0.5a.

We know that this distance is 120 m, so we can set up the equation 0.5a = 120 and solve for a:

a = 120 / 0.5 = 240 m/s^2

So, the acceleration of the body is 240 m/s^2.