The navigation rules for countries in the Unites States are compiled in the U.S. Coast Guard. There are actually boating courses that are recognized by the U.S Coast Guard. One of the things they discuss there is the emergency aids every boat should have depending on the size and purpose. For recreational vessels with lengths measuring less than 39.4 feet, they must carry aboard an efficient sound producing device. This will serve as your signal when emergencies happen and you have to get the attention of nearby boat vessels. Hence, for practical purposes, every boat should have a whistle or a horn.
She threw the marshmallow at a speed of around 4.76 m/s.The formula for the horizontal range gives the velocity.
<h3>What is projectile motion?</h3>
The motion of an item hurled or projected into the air, subject only to gravity's acceleration, is known as projectile motion.
The item is known as a projectile, and the course it takes is known as a trajectory. Falling object motion is a simple one-dimensional kind of projectile motion with no horizontal movement.
Given data;
The marshmallow was thrown at a distance of 2 meters
Range,R = 3 m
Initial velocity,u
The angle at which the marshmallow was thrown,θ = 30°
The acceleration due to gravity,g = 9.81 m/s²
The projectile's motion is divided into two parts: horizontal and vertical motion.

Hence, she throws the marshmallow at a speed of 4.76 m/sec.
To learn more about the projectile motion refer to the link;
brainly.com/question/11049671
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Answer:
Explanation:
Parameters given:
Mass of Puck 1, m = 1 kg
Mass of Puck 2, M = 1 kg
Initial velocity of Puck 1, u = 20 m/s
Initial velocity of Puck 2, U = 0 m/s
Final velocity of Puck 1, v = 5 m/s
Since we are told that momentum is conserved, we apply the principle of conservation of momentum:
Total initial momentum of the system = Total final momentum of the system
mu + MU = mv + MV
(1 * 20) + (1 * 0) = (1 * 5) + (1 * V)
20 = 5 + V
V = 20 - 5 = 15 m/s
Puck 2 moves with a velocity of 15 m/s
When light travels from a medium with higher refractive index to a medium with lower refractive index, the critical angle is the angle of incidence above which light is reflected only (no refraction occurs), and the value of this critical angle is given by

where n2 is the refractive index of the second medium and n1 is the refractive index of the first medium.
In this problem, the first medium is the glass (

), while the second medium is oil (

), therefore the critical angle is given by