A particle is projected from ground with some initial velocity making an angle of 45o with the horizontal. It reaches a height of 7.5 m above the ground while it travels a horizontal distance of 10 m from the point of projection. The initial speed of the projection is
Given that,
Angle θ=450
Horizontal distance x=10m
Vertically distance y=7.5m
Acceleration due to gravity g=10m/s2
Now,
y=(tanθ)x−(g2u2cos2θ)x2
7.5=1×10−10(2u2×12)×100
7.5−10=−1000u2
u2=10002.5
u=20m/s
Hence, the initial speed of the projection is 20 m/s