1.

Bullet moving with a velocity of hundred metre per second the strike wooden plank after passing through the plank of 1 metre length its velocity reduced to 50 metres per second. calculate the average retardation of the bullet while passing through the plank.how much time it take to reach the other end of the plank​

Answer»

Answer:

Given :

➡️ initial velocity = u = 100 m/s

➡️ final velocity = v = 50 m/s

➡️ distance = s = 1 metre

To find :

➡️ AVERAGE retardation while passing through the plank(a)

➡️ time taken while passing through the plank (t)

Solution :

According to newton's 3rd law of motion,

v square - u square = 2as

substituting the VALUES of v,u and a, we get

{(50)×(50)-(100)×(100)} m/s = (2×a×1)m/s

that is, (2500 - 10000)m/s = (2a)m/s

that is, a = -7500/2 m/s square

that is, a = -3725 m/s square

HENCE, average retardation of the bullet while passing through the plank is - 3725 m/s square

According to newton's first law of motion, we have

v=u+at

Now substituting the values of v,u and a, we get

50m/s = (100 +(-3725)t) m/s

that is, 50m/s - 100 m/s = -3725t m/s

that is, 50m/s = 3725×t m/s

that is, t = 3725/50 s = 78.5

Hence, time taken while passing through the plank is 78.5 second.


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