An open knife edge of mass 200 g is dropped from height 5m on a cardboard. If the knife edge penetrates distance 2m into the card board, the average resistance offered by the cardboard to the knife edge is (g = 10m//s^(2))

An open knife edge of mass 200 g is dropped from height 5m on a cardbo

1.	An open knife edge of mass 200 g is dropped from height 5m on a cardboard. If the knife edge penetrates distance 2m into the card board, the average resistance offered by the cardboard to the knife edge is (g = 10m//s^(2))
Answer» 7 N 25N 35 N None Solution :`U=sqrt(2gh),` using `v^(2)-u^(2)=2as` retardation due to air RESISTANCE `a^(1)=g+a` Force due to air resistance = Ma