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A railway carriage of mass 9000kg moving with a speed of `36kmh^(-1)` collides with a stationary carriage of the same mass. After the collision, the two get coupled and move together. What is this common speed ? What type of collision is this? |
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Answer» Here, `m_(1)=9000kg.` `u_(1)=36km//h=10m//s` `m_(2)=9000kg, u_(2)=0, v_(1)=v_(2)=v=?` From conservation of linear momentum, `(m_(1)+m_(2))v=m_(1)u_(1)+m_(2)u_(2)=m_(1)u_(1)` `v=(m_(1)u_(1))/((m_(1)+m_(2)))=(9000xx10)/(9000+9000)=5ms^(-1)` Total KE before collision `=(1)/(2)m_(1)u_(1)^(2)+(1)/(2)m_(2)u_(2)^(2)=(1)/(2)xx9000xx10^(2)` `=4.5xx10^(5)J` Total KE after collision `=(1)/(2)(m_(1)+m_(2))v^(2)` `=(1)/(2)(9000+9000)xx5^(2)=2.25xx10^(5)J` As KE after collision `lt` KE before collision `:. ` Collision is inelastic. |
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