the velocity of the body moving in a straight line with a constant acceleration, is 10 m/s at a certain instant 't' . after 5 second the velocity become 20 m/s, the velocity 3 second before 't' was?

Answer 1

clearly, the acceleration is ((20-10)m/s)/((5-0)s) = 10/5 = 2 m/s^2

so at t-3, v = 10-3*2 = 4 m/s