A bullet of mass 20 g moving with a speed of 75 ms-1 hits a fixed wooden plank and
comes to rest after penetrating a distance of 5 cm. What is the average resistive force
exerted by the wooden plank on the bullet?
TNSCERT Class 10 Physics Ch 15 Laws of Motivation and Gravitation
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m= 20 g = 20/1000 kg = 0.02 kg
u = 75 m/s
v= 0
s = 5 cm = 5/100 m = 0.05 m
as, v² -u² = 2as
⇒a = [(0)² - (75)²]/(2×0.05)
= -(75×75)/(0.1) = -562.5 m/s²
now, resistive force,F = m×a
= 0.02×(-562.5) = -11.25 N
negative shows the direction of force is in the opposite to the motion.
u = 75 m/s
v= 0
s = 5 cm = 5/100 m = 0.05 m
as, v² -u² = 2as
⇒a = [(0)² - (75)²]/(2×0.05)
= -(75×75)/(0.1) = -562.5 m/s²
now, resistive force,F = m×a
= 0.02×(-562.5) = -11.25 N
negative shows the direction of force is in the opposite to the motion.
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