A particle is projected at an angle of 600  above the horizontal with a speed of  10ms-1.. After sometime the direction of its velocity makes an angle of 300 above the horizontal. The speed of the particle at this instant is:

given initial velocity=u=10m/s; initial θ=600  ; α=300 Let v be the velocity of the projectile when it makes an angle   300  with the Horizontal.  Since horizontal component velocity of projectile remains unchanged vcos300=ucos600 substitute u =10, v  cos  300=10cos600       v32=10×12  v=103ms−1