A particle is projected with a velocity 40 m/s at an angle 30o with the horizontal. Find the change in velocity when it is at a height of 15 m from the ground, (g = 10 m/s2)

Horizontal velocity remains constantVertical velocity changesInitial vertical velocity  usinθ=40sin300                                              = 20 m/sAt height 15 m its vertical velocity uy2 = 202−2g15= 400 – 300 uy2 = 202−2g15Change in velocity = 20 – 10 = 10 m/s.