football hemets have pads that are filled with air and thick foam so when they are hit the foam asorbs the hit and the air keeps the hard outer shell of the helmet from hiting the players head
Answer: velocity of the car is 113.33m/s
Explanation:
From Doppler effect,
in the case which the source is moving towards the observer at rest
f2 = v/(v-vs) *f1
where f2 is the final observed frequency
f1 is the initial observed frequency
v = 340m/s (speed of sound in air)
vs = velocity of the source of sound.
rearranging the above equation
f2*(v - vs) = f1* v
vs = (f1* v/f2) - v
but f1 = 80Hz
f2 = 60Hz
v = 340m/s
substituting,
vs = (80 x 340)/60 - 340
vs = 453.33 - 340
vs = 113.33m/s
velocity of the car is 113.33m/s
When red light illuminates a grating with 7000 lines per centimeter, its second maximum is at 62.4°. What is the wavelength of this light?
ans: 633nm
Answer:
absorb more heat and get heated quickly
Explanation:
