Question

a projectlie is fired horizontally from the top of a hill with valocity 98m /s. the height of hills is 400m. calculate 1.time taken to reach the ground, 2.distance from the hill where the projectile falls on the ground,3.the valocity with which it's strick the ground

Answer 1

Hello!

• Height, h = 400 m

• Time taken to reach the ground = t

• Initial velocity in the vertical direction, uᵥ = 0

• Initial speed in horizontal direction, uₓ = 98 ms⁻¹

Now,

✓ Height :-

h = uᵥt + $\dfrac{\sf 1}{\sf 2}$gt²

⇒ 400 = 0 + 0.5 × 9.8t²

⇒ t = 8.94 sec = $\boxed{\sf 9 \:sec}$

✓ Final velocity in vertical direction :-

vᵥ = uᵥ + gt

⇒ 0 + 9.8 × 9 = $\boxed{\sf 88.2\: ms^{-1}}$

✓ Net velocity when projectile reaches ground :-

V = $\sqrt {\sf v_{x}^{2} + \sf v_{y}^{2}}$ = $\boxed{\sf 132.6\: ms^{-1}}$

✓ Distance travelled in horizontal direction :-

s = uₓt = 98 × 9 = $\boxed{\sf 882 \:m}$

Cheers!