It is known that the chord length of bow is 4.3m and 7m. How to calculate the circumference of bow? Please write the formula and explanation,

It is known that the chord length of bow is 4.3m and 7m. How to calculate the circumference of bow? Please write the formula and explanation,

It is known that the chord length of the bow is L = 4.3m and the height is h = 1.7m. How to calculate the circumference of the bow?
The radius of arc is r, and the center angle of arc is a
R^2=(R-H)^2+(L/2)^2
R^2=R^2-2*R*H+H^2+L^2/4
2*R*H=H^2+L^2/4
R=H/2+L^2/(8*H)
=1.7/2+4.3^2/(8*1.7)
=2.2096m
A=2*ARC SIN((L/2)/R)
=2*ARC SIN((4.3/2)/2.2096)
=153.33 degrees
Circumference of bow = 2 * pi * r * A / 360 + L
=2*PI*2.2096*153.33/360+4.3
=10.213m

Given chord length, arch height and radius, how to find arc length

L = arcsin (chord length / 2R) * 4 * pie * r

The formula of circular motion
Explain what the letters stand for

F = ma f centripetal force m mass a centripetal acceleration
A = w ^ 2R w angular velocity R radius
A = V ^ 2 / R V linear velocity
v=wr

Physical quantity describing circular motion
Period, frequency and rotational speed -- scalar of process and the relationship between variables

Period T is the time taken by an object to move for one week
Frequency is the number of turns in a second
Speed, refers to the number of turns (revolutions) within the specified time

Among the following physical quantities, what is the physical quantity describing the speed of circular motion?
A cycle, speed, radius
B period, radius
radius
frequency

D. Notice the speed. The radius has nothing to do with the speed

What physical quantity does not change in circular motion
The answer is responsible

The orbit curvature is invariable, or the radius is invariable

What physical quantities are conserved when a satellite moves in a circle under the action of gravity

Quality
mechanical energy
density
volume
······

In circular motion, what physical quantity is perpendicular to the plane of rotation,

Angular velocity. The angle of rotation per unit time
The magnitude of angular velocity: ω = V / r = 2 π / T
Where V is the linear velocity, R is the radius, and t is the period of uniform circular motion
Direction of angular velocity: hold the right hand, let the four fingers around the same direction as the direction of velocity, then the direction of thumbs up is the direction of angular velocity
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In addition to angular velocity, there is also a quantity to meet the requirements of the subject. But this quantity may not be learned in high school
Angular momentum
Angular momentum L = m * r × v = m * r * V * sin θ
M is the mass of the object in circular motion
R is the radius of rotation
V is the linear velocity of rotation
In uniform circular motion, θ = 90 degrees, so the angular momentum L = MRV
On the direction of L: R V L forms the right hand helix rule. Hold the right four fingers tightly so that the direction of V is the same as the surrounding direction of the four fingers, then the direction of L is the direction of the thumbs up

What is 1 / 2 circular motion?
There are several situations in which a small ball does not leave its orbit. One of them is to do 1 / 2 circular motion. Why can this kind of motion be carried out? If it is calculated according to kinetic energy and potential energy, why can't it be 4 / 3 or something?
No, it's a quarter

When the ball moves upward from the bottom of the orbit at a certain initial velocity, its kinetic energy gradually decreases and transforms into its own gravitational potential energy. According to 1 / 2 * MVT ^ 2-1 / 2 * MV0 ^ 2 = - MGH, if the ball does not move out of the orbit, then this

R * W ^ 2 = a in circular motion
Radius times Omega's Square equals acceleration. How do you get this formula?

In circular motion, the centripetal acceleration is a = V & # / R
v=rw
Then a = V & # 178 / r = (RW) &# 178 / r = RW & # 178;