Question

A man is throwing a spear from the top of a cliff, 5 metres from ground, at a 20° angle towards a fish that is 35 metres away. at what Velocity must the person throw to hit the fish and how long will it take?​

Answer 1

Horizontal component of the initial velocity=v ×cos20°

horizontal displacement= 35m

time taken. (t)=35÷(v×cos20°)

vertical component of the initial velocity= v×sin20°

vertical displacement= -5m(since it is opposite to the direction of the initial velocity. )

application of s=ut+1/2at×t. vertically,

-5=vsin20°×t -1/2 gt×t

-5= vsin20×35/vcos20-1/2×10×35×35/(vcos20×vcos20)

simplify further to obtain v and hence find the time taken