Question
A bullet initially moving with a velocity $20 \ m/s$ strikes a target and comes to rest after penetrating a distance $10 \ cm$ into the target. Calculate the retardation caused by the target.
✓
Answer
Initial velocity$ u = 20 m/s$
Final velocity $v = 0$
Distance travelled $s = 10 cm = 0.1 m$
Let acceleration be 'a'.
Using the third equation of motion,
$v^2- u^2= 2as$
We get,
$(0)^2 - (20)^2 = 2(a) (0.1)$
$a = -(400/0.2) m/s^2$
$a = -2000 m/s^2$
Thus, retardation $= 2000 m/s^{-2}$
Final velocity $v = 0$
Distance travelled $s = 10 cm = 0.1 m$
Let acceleration be 'a'.
Using the third equation of motion,
$v^2- u^2= 2as$
We get,
$(0)^2 - (20)^2 = 2(a) (0.1)$
$a = -(400/0.2) m/s^2$
$a = -2000 m/s^2$
Thus, retardation $= 2000 m/s^{-2}$
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