Answer:
8.91 J
Explanation:
mass, m = 8.20 kg
radius, r = 0.22 m
Moment of inertia of the shell, I = 2/3 mr^2
= 2/3 x 8.2 x 0.22 x 0.22 = 0.265 kgm^2
n = 6 revolutions
Angular displacement, θ = 6 x 2 x π = 37.68 rad
angular acceleration, α = 0.890 rad/s^2
initial angular velocity, ωo = 0 rad/s
Let the final angular velocity is ω.
Use third equation of motion
ω² = ωo² + 2αθ
ω² = 0 + 2 x 0.890 x 37.68
ω = 8.2 rad/s
Kinetic energy,
K = 0.5 x 0.265 x 8.2 x 8.2
K = 8.91 J
Refraction refers to C. the bending of light rays when they pass from one medium into another
Explanation:
Refraction is a phenomenon typical of wave. Refraction occurs when a wave travels through the boundary between two different mediums. When this occurs, the wave changes speed, wavelength and direction (but the frequency remains the same).
In particular, the direction of the refracted ray is determined by Snell's Law:
where
is the index of refraction of the 1st medium
is the index of refraction of the 2nd medium
is the angle of incidence, which is the angle between the direction of the incident wave and the normal to the boundary
is the angle of refraction, which is the angle between the direction of the refracted wave and the normal to the boundary
Therefore, the correct description of refraction is
C. the bending of light rays when they pass from one medium into another
Learn more about refraction:
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Answer:
A. The box experiences more friction on the carpeted floor
Explanation:
Friction is the force that opposes the motion of an object when it slides along a surface. The magnitude of the friction is given by
where m is the mass of the object, g is the acceleration due to gravity, and is the coefficient of friction, which depends on the type of material of the surface: the larger this coefficient, the stronger the friction, the more difficult is to push the box along the surface. Generally, a smooth surface has a lower coefficient of friction, while a rough surface has a larger coefficient of friction.
In this case, Ethan find it easier to push the box on the marble floor, because marble is smoother than the carpet and so friction is weaker, while for the carpeted floor the coefficient of friction is larger and so the friction is stronger, making it more difficult to push the box.