Final answer:
To find the final speed of a body undergoing constant acceleration, we use the formula v = u + at. With an initial speed of 40 m/s and acceleration of 4 m/s² over 10 s, the body's final speed is 80 m/s.
Step-by-step explanation:
The question involves calculating the final speed of a body after a certain time interval when it is subject to a given acceleration. The formula used for this calculation is derived from the kinematics in physics. Here, the equation v = u + at is applicable, where v is the final velocity, u is the initial velocity, a is the acceleration, and t is the time.
Given in the question, the body has an initial speed u = 40 m/s, an acceleration a = 4 m/s2, and the time taken is t = 10 s. Applying these values to the formula, we get:
v = u + at
v = 40 m/s + (4 m/s2 * 10 s)
v = 40 m/s + 40 m/s
v = 80 m/s
Therefore, after 10 seconds, the body's speed will be 80 m/s.