Question

CLASS 9 CHAPTER 9 FORCES OF LAW AND MOTION


Q.1): ANSWER THESE QUESTIONS IN NUMERICAL FORM


a)A bullet of mass 10 g travelling horizontally with a velocity of
150 m s-1 strikes a stationary wooden block and comes to rest
in 0.03 s. Calculate the distance of penetration of the bullet
into the block. Also calculate the magnitude of the force exerted
by the wooden block on the bullet.



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Answer 1

v = u + at

v = 0, u = 150 m/s, t = 0.03s, a = ?

a = -150/0.03

a = -5000 m/s² (retarding)

Stopping distance for an object, s = u²/2a

= 22500/2*5000 = 2.25 m

Force = ma

= 10 * 10⁻³ * (-5000)

= -50 N