Explanation:
The speed of a wave is given by :
......(1)
(i) Here, the wavelength of a sound wave in air reduces by a factor of 3. Equation (1) becomes :

Wavelength and frequency are inversely proportional to each other. So, if wavelength of a sound wave in air reduces by a factor of 3, then the frequency will increases by a factor of 3.
(ii) It remains the same.
Answer:
c
Explanation:
Friction is caused by how rough and object is, and how much the object weighs, as this causes it to drag more.
The value of cos θ in the given figure is 0.98.
<h3>
What is cosine of an angle?</h3>
The cosine of an angle is defined as the sine of the complementary angle.
The complementary angle equals the given angle subtracted from a right angle, 90.
cos θ = sin(90 - θ)
For example, if the angle is 30°, then its complement is 60°
cos 30 = sin(90 - 30)
cos 30 = sin 60
0.866 = 0.866
<h3>Cosine of an angle with respect to sides of a right triangle</h3>
cos θ = adjacent side / hypotenuse side
adjacent side of the given right triangle is calculated as follows;
adj² = 10² - 2²
adj² = 100 - 4
adj² = 96
adj = √96
adj = 9.8
cos θ = 9.8/10
cos θ = 0.98
Thus, the value of cos θ in the given figure is 0.98.
Learn more about cosine of angles here: brainly.com/question/23720007
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The equation for force is F=ma. Because we have the value of mass (0.42 kg) and the acceleration (14.8 m/s^2), simply plug them into the equation for force to get

The answer is 6.22 N because newtons are the unit used to measure force.