In: Physics
A grappling hook is fired from a cannon at ground level with an initial speed of 40 m/s at an angle of 50 degree above the ground. It is a fired at a vertical cliff. The cliff is very high and we are very close. So we are sure that the hook will hit the face of the cliff.
Vix = initial velocity in X-direction, Viy = initial velocity in Y-direction
Vi = initial velocity of hook = 40 m/s
in the triangle ABC, AC = adjacent = Vix , BC = opposite = Viy , AB = hypoteneuse = Vi
using trigonometric ratio , sin50 = BC/AB = Viy / Vi so Viy = Vi sin50
Viy = 40 x sin50 ( since Vi = 40 m/s)
Viy = 40 x (0.766) = 30.64 m/s
similarly using , cos 50 = AC/AB = Vix/Vi
Vix = Vi cos50
Vix = 40 cos50 (since Vi = 40 m/s)
Vix = 40 (0.643) = 25.71 m/s
to calculate the height which is in Y-direction , we need to use kinematics equation
considering the motion of hook from A to P along Y-direction. we list the data as
Viy = 30.64 m/s , ay = -9.8 m/s2 (acceleration due to gravity) , t = 4 sec , Yo =0 m ,Y = ''h'' (height)
so using the kinematics equation , Y = Yo + Viy t + (0.5) ay t2
h = 0 + (30.64 m/s)(4 sec) + (0.5) (-9.8 m/s2 ) (4 sec)2
h = 44.16 m
calculating Y-component of velocity at time of impact :-
considering the motion of hook from A to P along Y-direction. we list the data as
Viy = 30.64 m/s , ay = -9.8 m/s2 (acceleration due to gravity) , t = 4 sec , Vfy = ?
using the kinematics equation :- Vfy = Viy + at = 30.64 m/s + (-9.8 m/s2 ) (4 sec)
Vfy = -8.56 m/s
graph :-