I think the answer is 28 miles
Answer:
1)
from the positive x-axis.
2) 
Explanation:
Given:
speed of rowing in still water, 
1)
speed of water stream, 
we know that the direction of resultant of the two vectors is given by:

where:
the angle of resultant vector from the positive x-axis.
angle between the given vectors
When the rower wants to reach at the opposite end then:

so,




from the positive x-axis.
2)
Now the resultant velocity of rowing in the stream:



Therefore time taken to cross a 4 miles wide river:



Answer:
Diaphragm or Iris: Many microscopes have a rotating disk under the stage. This diaphragm has different sized holes and is used to vary the intensity and size of the cone of light that is projected upward into the slide.
Explanation:
Answer:
(i) The maximum acceleration upward is 2.02 m/s².
(ii) The maximum acceleration downward is 1.39 m/s².
Explanation:
Let a be the maximum acceleration of the elevator.
The mass of the person at ground is 150 lb. We have to convert the mass into kg,
1 lb = 0.453592 kg
150 lb = 68 kg
170 lb = 77 kg
120 lb = 54 kg
(i) The person experience a force due to Earth's gravity in the downwards direction. The magnitude of this force is:
F₁ = mg = 68 x 9.8 = 666.4 N
The weight of the person decreases as the elevator is moving upwards. So, the force experienced by the person in this case due to gravity is:
F₂ = 54 x 9.8 = 529.2 N
Applying Newton's force equation;
(F₁ - F₂) = ma
(666.4 - 529.2) = 68 x a
a = 2.02 m/s²
(ii) The weight of the person increases as the elevator is moving downwards. So, the force experienced by the person in this case due to gravity is:
F₂ = 77 x 9.8 = 754.6 N
Applying Newton's force equation;
(F₁ - F₂) = ma
(666.4 - 754.6) = 68 x a
a = -1.30 m/s²
Answer:
a) # buses = 7
Explanation:
For this exercise we use the kinematic equations, let's find the time it takes to reach the same height
y =
t - ½ g t²
Let's decompose the speed, with trigonometry
v₀ₓ = v₀ cos θ
= v₀ sin θ
v₀ₓ = 40 cos 32
v₀ₓ = 33.9 m / s
= 40 sin32
= 21.2 m / s
When it arrives it is at the same initial height y = 0
0 = (
- ½ gt) t
That has two solutions
t = 0 when it comes out
t = 2
/ g when it arrives
t = 2 21.2 /9.8
t = 4,326 s
We use the horizontal displacement equation
x = vox t
x = 33.9 4.326
x = 146.7 m
To find the number of buses we can use a direct proportions rule
# buses = 146.7 / 20
# buses = 7.3
# buses = 7
The distance of the seven buses is
L = 20 * 7 = 140 m
b) let's look for the scope for this jump
R = vo2 sin2T / g
R = 40 2 without 2 32 /9.8
R = 146.7 m
As we can see the range and distance needed to pass the seven (7) buses is different there is a margin of error of 6.7 m in favor of the jumper (security)