42. If a ball is thrown vertically upwards with a velocity of 40 m/s, then velocity of the ball after two seconds will be ( g = 10 m/s2 )

42. If a ball is thrown vertically upwards with a velocity of 40 m/s, then velocity of the ball after two seconds will be  ( g = 10 \(m/s^2\) )

(a) 15 m/s

(b) 20 m/s

(c) 25 m/s

(d) 28 m/s

Answer :  (b) 20 m/s

v = u + at

= 40 - 10 (2)

= 20 m/s