A grasshopper leaps into the air from the edge of a vertical cliff. Assume that
d1=7.15cm
, d2=1.04m
, and that
θ=49∘

A) what is the initial speed of the grasshopper?
B) what is the height of the cliff?

Respuesta :

Maximum height reached h = 7.15cm = 0.0715 m The horizontal distance b = 1.04 m Angle of jump = 49 degrees. We have v^2 = 2gh which here is (vsin theta)^2 = 2gh 
v^2 = (2 x 9.81 x 0.0715) / sin^2 49 = 1.402 / -0.95^2 = 1.55 => v = 1.24 m/s
 Time taken for flight = b / v Cos theta = 1.04 / (1.24 x cos49)
  = 1.04 / 0.8135 =1.27 s
 Time to reach maximum height = vsin theta / g = (1.24 x 0.95) / 9.8 = 0.12 s
 Now time taken for top to ground = 1.27 - 0.12 = 1.15 s
 So the total height H =1/2 gt = 1/2 x 9.8 x 1.15 = 5.635.
 Now the height of the cliff = 5.635 - 0.0715 = 5.56 m