The Doppler effect is the term that best describes the change in frequency of waves when there is motion between the source of the waves and the observer. The correct option among all the options that are given in the question is the first option or option "a". I hope the answer helps you.
Λ = 3*10^8 / 9*10^8 = 1/3 m
no. of wavelengths = 60/(1/3) = 180
Answer:
mark two options:
B. TSN and ISW
D. ISN and TSW
Explanation:
Recall the definition of vertical angles as: <em>those angles opposed by the vertex, and which are the result of two lines that intersect</em>.
In the figure given there are two pairs such angles, one pair I depicted in red, and the other one in blue, while the intersecting lines are shown in green. Notice that when two lines intersect, there are always two pairs of vertical angles being generated.
Therefore, according to the notation given, two boxes need to be checked in the set of options:
1) the one corresponding to : TSN and ISW (blue ones in the attached image)
and
2) the one corresponding to ISN and TSW (red ones in the attached image)
Helpful friction would be the friction on something that you wanted to stop (a car) while unhelpful friction is friction on something that you want to keep going (a curling rock)
Answer:
A 2 N force pulling and a 10 N force pulling left while a 12N force pulls right.