Question

A fisherman casts his bait toward the river at an angle of 25° above the horizontal. The bait and hook reach a maximum height of What was the initial velocity with which the bait was cast? Assume that the fishing line exerts no appreciable drag force on the bait and hook.

Answer 1

the vertical component of the casting velocity will be reduce to zero at point h by the force of gravity.

If we use the kinematic equation

vf² = vi² +2as

and realize that the final vertical velocity is zero

and the initial vertical velocity is vsinθ

where θ is the angle of cast above the horizon

0 = vsin25 + 2(-9.8)h

h = 0.423v / 19.6

h = 0.02156v

so the missing potential heights and the associated answer velocities are

v = 19 m/s...h = 0.410 m

v = 8.3 m/s...h = 0.179 m

v = 6.9 m/s...h = 0.149 m

v = 8.4 m/s...h = 0.181 m

choose the one that fits the question

or use the method to find the correct velocity based on the actual height reference frame.