Question

A bullet of 10g strikes a sand-bag at a speed of 10m/s and gets embedded after traveling 5 cm.calculate
A)the resistive force exerted by the sand on the bullet
B) the time taken by the bullet to come to rest.

Answer 1

HY DEAR ...



Mass of bullet should be =10gm=0.01kg
initial velocity (U)of bullet=1000m/s
final velocity (V)=0m/s(because it has stopped after striking sand)
displacement of bullet=5cm=0.05m
a)using 2as=V ²-U²
2(a)(0.05)=0²-1000²
2a(5/100)=-1000000
2a(1/20)=-1000000
a(1/10)=-1000000
a=-10000000=-10power7
acceleration of bullet is -10power7or -10000000
by using F=ma
F=0.01(10000000)
F=1/100(10000000)
F=-100000N
there fore resistive force of bullet =-100000N

b)by using a=v-u/t
-10000000=0-1000/t
-10000000=-1000/t
-10000=t
or
t=-10⁴seconds

HOPE , IT HELPS ...