<span>Even in space, there is still presence of gravity. The
cause of weightlessness is not how far above the earth the space shuttle is but
rather how fast it is travelling. The shuttle is in free fall causing
weightlessness, but it is travelling fast enough to miss the earth as it falls.
Similarly, the airplane could also provide weightlessness if it went free fall
as well. However, that ends as the plane hits the ground. </span>
Answer:
126000 J
Explanation:
Applying,
Q = cm(t₂-t₁).................. Equation 1
Where Q = Amount of heat, c = specifc heat capacity of water, m = mass of water, t₁ = Initial temperature, t₂ = Final temperature.
From the question,
Given: m = 2 kg, t₁ = 25°C, t₂ = 40°C
Constant: c = 4200 J/kg.°C
Substitute these value into equation 1
Q = 2×4200(40-25)
Q = 2×4200×15
Q = 126000 J
Pitch is directly related to the frequency of the sound. In this item, we are given that the frequency of the sound is higher compared to those which are audible to the human being's ears. The pitch therefore of the dog's whistle is high.
On the other hand, the frequency and the wavelength of a certain wave are inversely proportional. This means that the high frequency wave will have a short wavelength.
Hence, the answer to this item would have to be "high pitch with a short wavelength"
The answer to this item is the second option.
Complete Question:
A 10 kg block is pulled across a horizontal surface by a rope that is oriented at 60° relative to the horizontal surface.
The tension in the rope is constant and equal to 40 N as the block is pulled. What is the instantaneous power (in W) supplied by the tension in the rope if the block when the block is 5 m away from its starting point? The coefficient of kinetic friction between the block and the floor is 0.2 and you may assume that the block starting at rest.
Answer:
Power = 54.07 W
Explanation:
Mass of the block = 10 kg
Angle made with the horizontal, θ = 60°
Distance covered, d = 5 m
Tension in the rope, T = 40 N
Coefficient of kinetic friction, 
Let the Normal reaction = N
The weight of the block acting downwards = mg
The vertical resolution of the 40 N force, 
Power, 
Refraction is said to occur when there is a change in the speed of light.
<h3>What is the angle of refraction?</h3>
We know that refraction is said to occur when there is a change in the speed of light as it travels form one medium to another.
Given that the refractive index of the rectangular glass block is 1.5. The angle of refraction can be obtained by the use of the Snell's law;
n = sin i /sinr
n = refractive index
sini = angle of incidence
sin r = angle of refraction
sinr = sini/n
sinr = sin 45/1.5
= 0.471
r = 28 degrees
b) Now;
sinr =sin 45/1.2
sinr = 0.589
r = 36 degrees
For the glass
sinr = sin 36/1.5
sin r = 0.392
r = 23 degrees
Learn more about angle of refraction:brainly.com/question/2660868
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