written 8.7 years ago by | • modified 4.9 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 8.7 years ago by | • modified 4.9 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 8.7 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