written 8.4 years ago by | • modified 4.5 years ago |
(i) Horizontal distance AB it travel from the foot of the tower.
(ii) The velocity with which it strikes the ground at B.
(iii) Total time taken to reach point B
written 8.4 years ago by | • modified 4.5 years ago |
(i) Horizontal distance AB it travel from the foot of the tower.
(ii) The velocity with which it strikes the ground at B.
(iii) Total time taken to reach point B
written 8.4 years ago by |
Given:
$U=20m/s \\ . α=30 $
Let O be the origin.
Hence $0 = (0, 0)$
Hence, $B = (X,-50)$ (from the figure)
Hence, $x = ?; y = -50$
Using equation of path,
$Y= x \tan α – 4.9 x^2/ (u \cosα)^2 \\ -50 = X \tan30 – 4.9 \times X^2 /(20cos30)^2\\ X = 75.76 m $
ii)
time = horizontal distance/horizontal speed
$T= X/(u \cos α)= 75.76/(20 \cos30)= 4.37 sec $
iii)
$Vx=Ux = 20 \cos30→ $ (because horizontal speed doesn’t change in a projectile motion)
$$Uy = 20 \sin30$$
$$Vy = ?$$
Using $v= u +at \\ Vy = Uy – g \times T \\ = 20\sin30 – 9.8 \times 4.37 \\ = -32.83 m/s = 32.83 m/s↓ \\ U = 37.12 m/s ↘ θ=62.2$