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NTA Abhyas 2020
Exam
NTA Abhyas
Year
2020
Subject
Physics
Chapter
Motion in One Dimension

NTA Abhyas 2020 · Physics · Motion in One Dimension

A wooden block of mass 10gm is dropped from the top of a tower 100m...

A wooden block of mass 10gm10gm is dropped from the top of a tower 100m100m high. Simultaneously, a bullet of mass 10gm10gm is fired from the foot of the tower vertically upwards with a velocity of 100ms−1100m{s}^{- 1} . If the bullet is embedded in it, how high will it rise above the tower before it starts falling? (g=10ms−2)\left(g = 10m{s}^{- 2}\right)

A wooden block of mass 10gm is dropped from the top of a tower 100m high. Simultaneously, a bullet of mass 10gm is

Correct answer

75

Step-by-step solution

Block and bullet will collide after 1s1s at height 95m95m from ground.

Velocityofblockbeforecollision = gt = 10m{s}^{- 1}<br/><br/>Velocityofbulletbeforecollision=u–gt=90ms−1<br /><br />Velocityofbulletbeforecollision = u – gt = 90m{s}^{- 1}

from conservation of linear momentum,

m(–10)+m(90)=2mv′⇒v′=40ms−1m\left(– 10\right) + m\left(90\right) = 2mv′ ⇒ v′ = 40m{s}^{- 1}

A wooden block of mass 10gm is dropped from the top of a tower 100m high. Simultaneously, a bullet of mass 10gm is

Thus height raised by the combined mass

h=v′22g=40×402×10=80mh = \dfrac{v{′}^{2}}{2g} = \dfrac{40 \times 40}{2 \times 10} = 80m

heightfromtower=75mheightfromtower = 75m
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