1.

A projectile is fired at a speed of 100 m/s at an angle of 37^(@) above the horizontal. At the highest point, the projectile breaks into two parts of mass ratio 1 : 3, the smaller piece coming to rest. Find the distance from the launching point to the point where the heavier piece lands.

Answer»

Solution :Internal forces do not affect the motion of the centre of mass, the centre of mass HITS the ground at a position where the original projectile would have landed. The range of the original projectile is

`X_(CM)=(2U^(2)sin theta COS theta)/(g)=(2xx10^(4)xx(3)/(5)xx(4)/(5))/(10)m=960m`
The centre of mass will hit the ground at this position. As the SMALLER block comes to rest after breaking, it falls down vertically and hits the ground at HALF of the range, i.e., at x = 480 m. If the heavier block hits the ground at `x_(2)`, then
`X_(CM)=(m_(1)x_(1)+m_(2)x_(2))/(m_(1)+m_(2))rArr 960 =((m)(480)+(3m)(x_(2)))/((m+3m))`
`therefore x_(2)=1120m`


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