6look
here
u=0
a=g
and s= 5m
using s=ut + 1/2 a t^2
find t = 1.01
find final velocity v = 9.89 m/s
then for motion in sand
using
v^2 = U^2 + 2as
find a = - 490m/s^2
a ball is dropped from a height of 5m onto a sandy floof and penentrates the sand upto 10 cm before coming to rest . find the retardation of the ball in sand assuming it to be uniform.
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3 Answers
39Using equations of motion, first find the final velocity of the ball just as it hits the sandy floor(u = 0, a = g, s = 5, v = ?). From thereon, use another equation of motion to find retardation (u = v found in previous, s = 0.1m, v = 0, a = ?).
6
49what gravity had taken 5 m to make, the sand destroys in 10 cm....
applying v2=2gS1=2aS2 we easily get the result in 1 step.. [:D]
we know g, S1 and S2 and thus, easily can calculate a!!
a= gS1S2=g50.1=50g=490.5 m/s2 [1][1]
