Question

a ball of mass 50 g is dropped from a height of 20m .a boy on the ground hits the ball vertically upwars with a bat with an average force of 200N so that it attains a vertical height of 45m .the time for which the ball remains in contact with the bat is take (g=10 m/s2)

Answer 1

from up to down U1=0
V1=velocity before hitting bat.
S1=distance before hitting bat.
V1²=U1²+2as
=0+2×10×20=400
V1=√400=20m/s
F=m×a
a=F/m=200/(50×10^-3)

=4000m/s²
U2= velocity after hitting bat
V2=velocity at top =0
S2=distance covered after hitting bat =45
U2²=-2×10×45=-900
U2=-√900=-30m/s.
time ,
-30=20-400×t
t=(-30-20)/-4000=-50/-4000=1/80.