Q.

When an object is shot from the bottom of a long smooth inclined plane kept at an angle 60° with horizontal, it can travel a distance x1 along the plane. But when the inclination is decreased to 30° and the same object is shot with the same velocity, it can travel x2 distance. Then x1:x2 will be           [2019]
 

1 1:23  
2 1:2  
3 2:1  
4 1:3  

Ans.

(4)

 v2-u2=2ax

For case I : v2=u2-2(gsinθ1)x1           [a=-gsinθ]

x1=u22gsinθ1                                                      [v=0]

For case II : v2=u2-(2gsinθ2)x2

x2=u22gsinθ2

  x1x2=sinθ2sinθ1=sin30°sin60°=13