Answer:
Part a)
H = 26.8 m
Part b)
error = 7.18 %
Explanation:
Part a)
As the stone is dropped from height H then time taken by it to hit the floor is given as
now the sound will come back to the observer in the time
so we will have
so we have
solve above equation for H
Part b)
If sound reflection part is ignored then in that case
so here percentage error in height calculation is given as
Answer:
She must be launched with a speed of 74.2 m/s.
Explanation:
Hi there!
The equations of the horizontal component of the position vector and the vertical component of the velocity vector are the following:
x = v0 · t · cos θ
vy = v0 · sin θ + g · t
x = horizontal distance traveled at time t.
v0 = initial velocity.
t = time.
θ = launching angle.
vy = vertical component of the velocity vector at time t.
g = acceleration due to gravity (-9.8 m/s²).
To just cross the 520-m gap, the maximum height of the flight must be reached halfway of the gap at 260 m horizontally (see attached figure).
When she is at the maximum height, her vertical velocity is zero. So, when x = 260 m, vy = 0. Using both equations we can solve the system for v0:
x = v0 · t · cos θ
Solving for v0:
v0 = x/ (t · cos θ)
Replacing v0 in the second equation:
vy = v0 · sin θ + g · t
0 = x/(t·cos(56°)) · sin(56°) + g · t
0 = 260 m · tan (56°) / t - 9.8 m/s² · t
9.8 m/s² · t = 260 m · tan (56°) / t
t² = 260 m · tan (56°) / 9.8 m/s²
t = 6.27 s
Now, let's calculate v0:
v0 = x/ (t · cos θ)
v0 = 260 m / (6.27 s · cos(56°))
v0 = 74.2 m/s
She must be launched with a speed of 74.2 m/s.
