The area of the circle with radius r is
A = πr²
The rate of change of area with respect to time is

The rate of change of the radius is given as

Therefore

When r = 10 ft, obtain

Answer: - 40π ft²/s (or - 127.5 ft²/s)
Find the average speed and the average velocity.
Average speed = distance / time
distance = 10 x 8000 m = 80,000 m
time = 20 min * 60 s/min = 1200 s
Average speed = 80,000 m / 1200 s = 66.67 m/s
Average velocity = displacement / time
Given that the race car made complete circles the final poin is the same initial point, then its displacement is zero and the average velocity is zero too.
Answer:
It is d. 0.80
Trust me i got it right took it and got it right
Answer:
The wavelength is 
Explanation:
From the question we are told that
The wavelength of the red laser is 
The spacing between the fringe is 
The spacing between the fringe for smaller laser point is 
Generally the spacing between the fringe is mathematically represented as

Here
is the distance to the screen
and d is the distance of the slit separation
Now for both laser red light light and small laser point D and d are same for this experiment
So

=> 
Where
is the wavelength produced by the small laser pointer
So

=> 