Correct Answer - 50
As the velocity of the ball changes from `vecv_1 to vecv_2`, the change in velocity `Deltavecv` is given by
`|Deltavecv| = sqrt(v_(1)^(2) + v_(2)^(2) - 2v_1v_2cos theta)`
where `v_1 = 30ms^(-1), v_2 = 40ms^(-1) and theta = 90^@`.
Then, `|Deltavecv| = 5 ms^(-1)`,
`a_(av) = |Deltavecv|/(Deltat) = 5/(0.01)`
`= 5 xx 10^2 ms^(-2)`.