The answer is A. wood
because there are three different courts: clay court, grass court, and hard court. wood isn't in there so that would be the answer.
The trains take <u>57.4 s</u> to pass each other.
Two trains A and B move towards each other. Let A move along the positive x axis and B along the negative x axis.
therefore,

The relative velocity of the train A with respect to B is given by,

If the train B is assumed to be at rest, the train A would appear to move towards it with a speed of 170 km/h.
The trains are a distance d = 2.71 km apart.
Since speed is the distance traveled per unit time, the time taken by the trains to cross each other is given by,

Substitute 2.71 km for d and 170 km/h for 

Express the time in seconds.

Thus, the trains cross each other in <u>57.4 s</u>.
Answer:
The greatest speed of the car is 19.36m/s
Explanation:
The maximum speed the car will attain without skidding is given by:
F= uN = umg ...eq1
But F = mv^2/r
mv^2/r = umg
Dividing both sides by m, leaves you with:
V= Sqrt(ugr)
Where u = coefficient of static friction
g = acceleration due to gravity
r = raduis
Given:
U = 0.82
r=0.82
g= 9.8m/s
V = Sqrt(0.82 × 9.8 × 45)
V = Sqrt(374.85)
V = 19.36m/s
HUHHHHHHHHHHHHHHHHHHHHH????????
It’s true. longer wavelength means a lower frequency, and a shorter wavelength means a higher frequency!